Catalytically Treating Water Contaminated With Halogenated Organic Compounds

ABSTRACT

Catalytically treating groundwater ( 10 ), surface water, or above surface water, contaminated ( 12 ) with halogenated organic compounds being members of chlorotriazine, chloroacetanilide, or halogenated aliphatic, herbicide groups, and, halogen containing analogs and derivatives thereof. Method: exposing contaminated water to catalytic amount of electron transfer mediator ( 18 ) under reducing conditions, to decrease concentrations of halogenated organic compounds. System: at least one electron transfer mediator ( 18 ) contained in at least one (in-situ or/and ex-situ) unit ( 20 ), for exposing to contaminated water under reducing conditions. Exemplary electron transfer mediators are porphyrinogenic organometallic complexes, being metalloporphyrins, metallocorrins, or metallochlorins. Exemplary metalloporphyrins are a [TMPyP], [TP(OH)P], [TPP], or [TBSP], free base porphyrin complexed to a transition metal (cobalt, nickel, iron, zinc, or copper). Implemented according to homogeneous or/and heterogeneous catalysis, via batch or flow mode. Reducing conditions naturally exist, or/and are anthropogenically produced, in the contaminated water. Applicable to in-situ groundwater permeable reactive barriers (PRBs) ( 22 ).

FIELD AND BACKGROUND OF THE INVENTION

The present invention relates to the field of environmental science and technology focusing on treating or remediating water contaminated or polluted with halogenated organic compounds, where the contaminated or polluted water is a form of groundwater, surface water, above surface water, or a combination thereof. More particularly, the present invention relates to a method of catalytically treating water contaminated with halogenated organic compounds, and a system thereof, wherein the halogenated organic compounds are selected from the group consisting of chlorotriazine herbicides, chloroacetanilide herbicides, halogenated aliphatic herbicides, halogen containing analogs thereof, halogen containing derivatives thereof, and combinations thereof. These herbicide type halogenated organic compounds, at room temperature and atmospheric pressure, are non-volatile particulate substances (nearly all) or liquids (some) which, at typical contaminant concentrations (e.g., ppb-ppm range) are mobile and soluble in water. The present invention is applicable for (in-situ or/and ex-situ) homogeneously or/and heterogeneously catalytically treating such contaminated water being a variety of different forms, such as groundwater (e.g., sub-surface water regions, reservoirs, or aquifers), surface water (e.g., rivers, lakes, ponds, pools, or surface water reservoirs), above surface water (e.g., above surface water reservoirs, or above surface sources or supplies of residential or commercial drinking water), or a combination thereof.

On-Going Problem of Water Contaminated or Polluted with Halogenated Organic Compounds:

Among the wide variety of different types of water contaminants or pollutants, halogenated (especially, chlorinated) organic compounds are arguably the most common, pervasive (widespread), persistent (e.g., having half-lives ranging from days to 10,000 years), proven or potentially hazardous (poisonous or toxic), undesirable contaminants or pollutants in various forms of water, such as groundwater (e.g., sub-surface water regions, reservoirs, or aquifers), surface water (e.g., rivers, lakes, ponds, pools, or surface water reservoirs), above surface water (e.g., above surface water reservoirs, above surface sources or supplies of residential or commercial drinking water), or combinations thereof. Many such forms of water either are, or lead to, sources of drinking water. Until the end of the 1960s, numerous halogenated (especially, chlorinated) organic compounds were applied in a wide variety of different agricultural and industrial processes, by exploiting their high performance, in addition to their relatively high stability and resistance to chemical and biological degradation. It is now recognized that these properties, which are essential to industry, have devastating effects on the environment, translating to undesirable short and long term health problems.

The fate of anthropogenic (human originating or synthesized) halogenated organic compound contaminants or pollutants in the environment is of great concern because of their proven or potential proven or potentially hazardous (poisonous or toxic) properties and characteristics. Discharge of these compounds into surface and sub-surface environments has led to extensive surface water and groundwater contamination or pollution. Largely based on the fact that groundwater accounts for about 95% of the earth's usable fresh water resources, groundwater contamination or pollution is a critical issue, and intensive efforts are continuously being invested in the development of improved and new technologies for treating or remediating water contaminated or polluted with halogenated organic compounds, where the contaminated or polluted water is a form of groundwater, surface water, above surface water, or a combination thereof.

Halogenated Organic Herbicides and Particular Groups Thereof:

An herbicide generally refers to a substance used to destroy plants, especially weeds. Accordingly, such a substance which destroys plants is considered as exhibiting herbicidal activity. As expected, there exists a plethora of numerous different types of herbicides. For convenience, and for the purpose of establishing some type of order when discussing or describing herbicides, or the various different subjects involving or relating to herbicides, the scientific community categorized and grouped numerous herbicides into various different individual herbicide groups, where each herbicide group is identified by at least one general characteristic or distinguishing feature or property, for example, chemical structure, which is common to each of the herbicide members in that herbicide group.

Of the numerous known herbicide groups, three particularly well known halogenated organic herbicide groups are: the chlorotriazine herbicide group, the chloroacetanilide herbicide group, and the halogenated aliphatic herbicide group, where each halogenated organic herbicide group is identified by the general characteristic or distinguishing feature or property of chemical structure, which is common to each halogenated organic herbicide member in that halogenated organic herbicide group. FIGS. 1, 2, and 3, are tables listing the compound ‘common’ name, chemical formula, and Chemical Abstract Service (CAS) number, and showing the chemical structure, of known halogenated organic herbicide members in each of these three respective halogenated organic herbicide groups. Each of these known halogenated organic herbicide members also has other, less commonly used, chemical names, for example, as assigned by CAS and IUPAC, which, although not listed herein, appear in published chemical literature and related prior art. Further details regarding chemical structures of halogenated organic herbicide members, halogen containing analogs thereof, and halogen containing derivatives thereof, in the following illustratively described three halogenated organic herbicide groups, are provided hereinbelow in the Description.

The chlorotriazine herbicide group, as identified and illustrated in FIG. 1, refers to and includes halogenated organic herbicides having the general chemical structure shown hereinbelow, wherein R₁-R₄ are each independently selected from the group consisting of a hydrogen atom [H] and an organic substituent:

The chloroacetanilide herbicide group, as identified and illustrated in FIG. 2, refers to and includes halogenated organic herbicides having the general chemical structure shown hereinbelow, wherein R₁-R₄ are each independently selected from the group consisting of a hydrogen atom [H] and an organic substituent:

The halogenated aliphatic herbicide group, as identified and illustrated in FIG. 3, refers to and includes halogenated organic herbicides having the general chemical structure shown hereinbelow, wherein n ranges from 1 to 4, and, A, B, R′, and R″, are each independently selected from the group consisting of a hydrogen atom [H] and an organic substituent, whereas at least one of A, B, R′, and R″ is a halogen atom (i.e., fluorine [F], chlorine [Cl], bromine [Br], or iodine [I]).

A—(C—R′—R″)_(n)—B

The scope of application of the present invention is particularly directed to the above illustratively described three halogenated organic herbicide groups and the halogenated organic herbicide members therein, halogen containing analogs thereof, halogen containing derivatives thereof, and combinations thereof, as being specific types or categories of the broader and more general category of halogenated organic compounds, which are of particular interest in the field of environmental science and technology focusing on treating or remediating contaminated or polluted water.

Halogenated Organic Herbicides as Problematic Water Contaminants:

Halogenated organic herbicides, in general, for example, encompassing all halogenated organic herbicide members in the above illustratively described three halogenated organic herbicide groups, and chlorinated organonitrogen herbicides (CONHs), in particular, for example, encompassing all halogenated organic herbicide members in the chlorotriazine herbicide group (especially triazines, such as atrazine and cyanazine) and in the chloroacetanilide herbicide group (such as alachlor and metolachor), are the most widely used agricultural chemicals (agrochemicals). The popularity of using triazine halogenated organic herbicides is based on their herbicidal effectiveness, commercial affordability, and lack of comparable alternatives. Halogenated organic herbicides, in general, and CONHs, in particular, are commonly used for pre- and post-emergence weed control during the growing of various crops, for example, corn, soybean, and sugarcane, and have become an integral component of modern agriculture worldwide. The U.S. Environmental Protection Agency (EPA) estimates that 36 and 16 million kilograms of atrazine and cyanazine, respectively, are dispersed among croplands annually across the nation [1]; application of alachlor tends to be similar to atrazine [2-4].

Halogenated organic herbicides, in general, and CONHs, in particular, and many of their degradation products, are non-volatile particulate substances (nearly all) or liquids (some) which, at typical contaminant concentrations (e.g., ppb-ppm range) are mobile and soluble in water. Many halogenated organic herbicides, for example, atrazine, cyanazine, and simazine (CONHs included in the chlorotriazine herbicide group (FIG. 1)), and, alachlor and metolachlor (CONHs included in the chloroacetanilide herbicide group (FIG. 2)), and their degradation products (especially higher water mobile halogen (in particular, chlorine) containing derivatives), are pervasive, persistent, proven or potentially hazardous (poisonous or toxic), undesirable contaminants or pollutants in various forms of water, such as groundwater (e.g., sub-surface water regions, reservoirs, or aquifers), surface water (e.g., rivers, lakes, ponds, pools, or surface water reservoirs), above surface water (e.g., above surface water reservoirs, or above surface sources or supplies of residential or commercial drinking water), or a combination thereof. Many such forms of water either are, or lead to, sources of drinking water.

Halogenated organic herbicides have been measured in drinking water sources at concentrations exceeding their EPA promulgated maximum contaminant levels (MCLs) [2, 4, 5]. The possibility of widespread water contamination or pollution, and consequent deterioration of water quality, because of the application of halogenated organic herbicides, and subsequent runoff of halogenated organic herbicides and their degradation products from agricultural fields, are driving the on-going need for studying about the distribution (pervasiveness), transport (mobility), fate (e.g., as relating to persistence, transformation, or/and degradation), ecological risk, and health effects, of halogenated organic compounds in water, particularly, in forms of water which either are, or lead to, sources of drinking water.

The persistence of halogenated organic herbicides, in general, and CONHs, in particular, and their degradation products, in groundwater or surface water has been widely reported [e.g., 1, 6-11]. Studies [6, 7, 12-14] by the U.S. Geological Survey (USGS) have shown that some parent CONHs, particularly atrazine, persist from year to year in soils and rivers, and that several CONH degradates are likewise persistent and mobile. Atrazine has a half-life of about 125 days, and because atrazine is not readily absorbed or adsorbed by soil particles, it is relatively mobile among sandy soils, further enabling atrazine to contaminate or pollute water. For example, in the US, atrazine has been found in the groundwater of all 36 river basins studied by the USGS, and the USGS estimates that persistence of atrazine in deep lakes may exceed 10 years. Similar findings were obtained for diethylatrazine, an atrazine degradation byproduct, and it was reported [1] that concentrations of the parent compounds atrazine, alachlor and cyanazine, were occasionally observed above their MCLs in the Minnesota River. Well water surveys [e.g., 8] have shown that many aquifers are contaminated with high levels of CONHs.

Numerous studies [e.g., 8, 9, 11-14] clearly indicate the on-going concern regarding possible health effects due to the presence of CONHs and their degradation products in groundwater or surface water. Many CONHs show acute and chronic toxicities at low concentrations [15-17], and they generally are known, or are suspected, to be carcinogenic, mutagenic, or/and teratogenic [1, 15-19]. Several studies [20-25] have implicated or shown specific CONHs (such as atrazine) or/and their degradation products as endocrine disruptors and teratogens in amphibians. Moreover, exposure to low levels of atrazine was found to induce sexual abnormalities in frogs [26-28]. Additional studies on the ecological impact of CONHs have implicated individual CONHs, as well as mixtures of CONHs, and their degradation products, as endocrine disruptors in fish, for example, leading to adversely affecting reproduction of game fish such as bass (Micropterus salmoides).

In the US, atrazine was greatly restricted from 1993, and its level in drinking water was regulated between 1993-1995. Several countries in the EU (European Union), in particular, France, Denmark, Germany, Norway, and Sweden, have already banned atrazine [26]. Despite such restrictions, regulations, and bans, atrazine (as just one of the numerous CONHs included in the broader and more general category of halogenated organic herbicides), remains a major hazardous water contaminant. Moreover, because conventional water treatment practices ordinarily do not remove soluble halogenated organic herbicides from the raw source waters being treated, concentrations of such herbicides in drinking water can be equivalent to those in the raw source waters [7, 29-31].

In spite of proven and potential environmental and health hazards, many halogenated organic herbicides, among the wide variety of different types of persistent water contaminants, currently remain in widespread international use, thereby perpetuating a continuously on-going problem. The main concern lies in the large quantities of halogenated organic herbicides, in general, and CONHs, in particular, and their degradation products, present in, or in close proximity to, forms of water which either are, or lead to, sources of water to which humans or/and animals are directly or indirectly exposed.

Problems of Treating or Remediating Groundwater:

Following application of halogenated organic herbicides to agricultural fields, eventually, as a result of rain or/and irrigation of the agricultural land, the mobile and soluble halogenated organic herbicides, and possible initial degradation products thereof, are dissolved and transported into and through surface and sub-surface soils, and typically become heterogeneously distributed among various sub-surface layers or regions by diffusion, adsorption, and desorption processes. Upon reaching groundwater (e.g., sub-surface water regions, reservoirs, or aquifers), dissolution and transport of such contaminants in the groundwater may generate extended, relatively large contaminant zones or regions, known as contaminant plumes. Main problems associated with treating or remediating groundwater are that such contaminant zones or regions (plumes) tend to be very difficult to locate, detect, characterize, and treat; heterogeneities are often present in groundwater environments; and long periods of continuous groundwater flow are often required for contaminants, and possible degradation products, to be sufficiently removed from contaminated groundwater. In contrast to river water, which has a turnover time on the order of two weeks, groundwater residence times are on the order of 10-1000 years.

Current Techniques for Treating or Remediating Water Contaminated with Halogenated Organic Compounds:

There exists a plethora of numerous different types of well known and used prior art techniques (methods, materials, compositions, devices, and systems) for treating or remediating water contaminated or polluted with halogenated organic compounds, such as halogenated organic herbicides, in general, and CONHs, in particular, and their degradation products, where the contaminated or polluted water is a form of groundwater, surface water, above surface water, or a combination thereof. Each particular technique is primarily based on principles, phenomena, mechanisms, and processes, in one of the following main categories: (a) physical/physical chemical, (b) biological, or (c) chemical. A common ultimate objective of each water treatment or remediation technique is to in-situ or/and ex-situ eliminate, or at least decrease, concentrations of the hazardous or potentially hazardous (poisonous or toxic) halogenated organic compound contaminants in the contaminated water. Following are brief descriptions of the above categorized techniques, along with selected examples of prior art teachings thereof, for treating or remediating water contaminated with halogenated organic compounds.

(a) Physical/Physical Chemical Techniques for Treating or Remediating Water Contaminated with Halogenated Organic Compounds:

Physical/physical chemical techniques for treating or remediating water contaminated or polluted with halogenated organic compounds are based on exploiting physical or physicochemical types of phenomena, mechanisms, and processes, such as filtration, for absorbing, adsorbing, and removing, the halogenated organic compounds; chemical destruction, whereby extreme conditions of temperature or/and pressure are used for breaking chemical bonds of the halogenated organic compounds; or/and photolysis, whereby UV (ultra-violet) light is used for breaking chemical bonds of the halogenated organic compounds. The halogenated organic compounds are ‘physically’ or ‘physicochemically’ removed or transported from the contaminated water to another medium, such as a filter, or are transformed, converted, or degraded, in the contaminated water to non-hazardous or/and less hazardous (poisonous or toxic) compounds.

An example of using filtration for treating or remediating water contaminated or polluted with halogenated organic compounds is based on activated carbon filtration. A typical activated carbon filter is made of tiny clusters of carbon atoms, in the bulk form of granular or powder sized particles derived from any number of various sources, creating a highly porous and active material with an extremely high surface area for contaminant adsorption. The contaminated water is exposed to the activated carbon filter, during which the halogenated organic compounds contaminants diffuse and are adsorbed by, and become concentrated on, the activated carbon, and are thereby removed from the contaminated water. After significant build up of the contaminants on the activated carbon, the contaminant containing de-activated carbon filter is removed from the contaminated water, and disposed of, or, flushed or otherwise treated (regenerated) to remove the contaminants and re-activate the carbon for re-use. A significant limitation of the activated carbon filtration technique is that the halogenated organic compound contaminants are essentially only transferred from the contaminated water to the carbon filter, without being converted or detoxified to non-hazardous or/and less hazardous environmentally acceptable compounds. Additionally, implementation of this technique requires resources (manpower and equipment) for removing, and disposing of, or, regenerating, the contaminant containing de-activated carbon filter.

An example of using chemical destruction for treating or remediating water contaminated or polluted with halogenated organic compounds is based on using extreme or destructive conditions of temperature or/and pressure, in the absence of chemical reagents, for breaking chemical bonds of, and thereby transforming, converting, or degrading, the halogenated organic compounds in the contaminated water to non-hazardous or/and less hazardous (poisonous or toxic) compounds. Such a technique has been proposed [32] for degrading atrazine (being an exemplary CONH included in the chlorotriazine herbicide group (FIG. 1)) under high temperature (150-200° C.) and pressure (3.0-6.0 MPa).

An example of using photolysis for treating or remediating water contaminated or polluted with halogenated organic compounds is based on the process of ultra-violet (UV) light photolysis (and photocatalysis as a specific type thereof). In particular, it has been shown that when aqueous solutions of soils contaminated with atrazine, wherein are included suspended metal oxide particles (e.g., titanium oxide [TiO₂], or zinc oxide [ZnO]), are exposed to UV light, the atrazine is physicochemically modified, via oxidative photocatalysis, resulting in formation of a variety of different atrazine transformation and degradation products [33]. A large solar plant for photocatalytic water decontamination, including degradation of atrazine, was studied [34]. A few selected more recent studies involving UV light photolysis (photocatalysis) of halogenated organic compounds are focused on: comparison of the kinetics of oxidative photodegradation of atrazine in aqueous Fe(ClO₄)₃ solutions and TiO₂ suspensions [35]; a porphyrin-phthalocyanine photochemical reaction catalyst for photocatalytically degrading atrazine [36]; and the dynamics and mechanism of ultraviolet photolysis of atrazine on soil surface [37, 38].

(b) Biological Techniques for Treating or Remediating Water Contaminated with Halogenated Organic Compounds:

Biological techniques for treating or remediating water contaminated or polluted with halogenated organic compounds are based on exploiting biological (microbiological) types of phenomena, mechanisms, and processes, involving the use of biological organisms (such as microbes, microorganisms, bacteria), for ‘biologically’ transforming, converting, or degrading, the halogenated organic compounds in the contaminated water to non-hazardous or/and less hazardous (poisonous or toxic) compounds.

Several different types of microorganisms are effective for treating water contaminated with halogenated organic compounds. For example, anaerobic type microorganisms are known for degrading CONHs. Important advantages of using microorganisms are that the process of dehalogenation (especially, dechlorination) occurs in-situ, and the compounds are typically completely degraded, thereby precluding the need for using another method for degrading intermediate degradation products of the halogenated organic compounds. However, a significant limitation of using microbiological techniques for treating contaminated water is that, typically, they are strongly influenced, and may be inactivated, by changes in environmental conditions, such as pH, temperature, and nutrient supply, which take place during the water treatment, especially during long term water treatment.

Regarding the limitation concerning changes in environmental conditions while using microbiological systems for treating water contaminated with atrazine, for example, Pranab et al. [39] state that “many studies were carried out so far on the biodegradation of atrazine in wastewater and bioremediation of atrazine contaminated soil. Most of these studies employed pure culture microorganisms except a few by mixed bacterial culture. Pure culture bacteria used atrazine as a sole source of carbon and/or nitrogen, but degradation was partial and mineralization happened only in a few cases. Atrazine biodegradation rate and the degree of degradation depended on the types of pure culture bacteria, presence and absence of various external carbon and nitrogen sources and their respective concentrations, carbon/nitrogen ratio, pH, and moisture content. Handling of pure culture bacteria in actual field conditions is a cumbersome job and atrazine mineralization in situ condition was almost non-existent. Mandelbaum et al. [40] observed mineralization of atrazine, only after mixing a number of pure culture strains among two hundred isolated strains.”

Another significant limitation of using microbiological systems for treating water contaminated with halogenated organic compounds is that high contaminant concentrations can be poisonous or toxic to the contaminant degrading bacteria. For example, it has been shown [41] that during dechlorination of trichloroethylene (TCE) and vinyl chloride (VC), acetylene is an abiotically formed intermediate species which can inhibit the biotic transformation, conversion, or degradation, of the initial halogenated organic compound contaminants.

(c) Chemical Techniques for Treating or Remediating Water Contaminated with Halogenated Organic Compounds:

Chemical techniques for treating or remediating water contaminated or polluted with halogenated organic compounds are based on exploiting non-catalytic chemical reaction, or (homogeneous or heterogeneous) catalytic chemical reaction, types of phenomena, mechanisms, and processes, involving the use of (inorganic or/and organic) chemical reagents, for ‘chemically’ transforming, converting, or degrading, the halogenated organic compounds in the contaminated water to non-hazardous or/and less hazardous (poisonous or toxic) compounds.

In a non-catalytic chemical reaction type of chemical technique, at least one of the chemical reagents is a main reactant which directly reacts (without a catalyst) with the halogenated organic compound contaminant(s) in a non-catalyzed chemical reaction, typically, a redox (reduction-oxidation) chemical reaction, for transforming, converting, or degrading, the halogenated organic compounds in the contaminated water to non-hazardous or/and less hazardous compounds. In a homogeneous or heterogeneous catalytic chemical reaction type of chemical technique, at least one of the chemical reagents is a participant, facilitator, or expeditor, functioning as a homogeneous or heterogeneous catalyst in a homogeneous or heterogeneous catalytic chemical reaction, typically, a homogeneous or heterogeneous redox (reduction-oxidation) catalytic chemical reaction, involving the halogenated organic compound contaminant(s), for transforming, converting, or degrading, the halogenated organic compounds in the contaminated water.

Herein, for the purpose of clearly understanding, without ambiguity, the following presentation of prior art teachings, as well as of the subject matter of the present invention, a homogeneous catalytic chemical reaction is wherein the catalyst (particularly, e.g., an electron transfer mediator) is an initially solid (typically, particulate) substance that is non-supported, non-matrixed, non-intercalated, or/and non-trapped, by another material, and subsequently becomes freely mobile and soluble throughout the contaminated water. A heterogeneous catalytic chemical reaction is wherein the catalyst (particularly, e.g., an electron transfer mediator) is an initially solid (typically, particulate) substance that is supported, matrixed, intercalated, incorporated, or/and trapped, and generally immobile, on or/and inside of a (particulate or/and non-particulate) solid support or matrix material which subsequently becomes dispersed (i.e., not dissolved) throughout the contaminated water. Ordinarily, the initially immobilized catalyst similarly becomes dispersed (i.e., not dissolved) throughout the contaminated water, but, may at least partially dissolve in the contaminated water, depending upon actual parameters and conditions of a given heterogeneous catalytic chemical reaction system.

Reductive Dehalogenation:

Currently, most chemical techniques used for treating or remediating water contaminated or polluted with halogenated organic compounds are based on reductive dehalogenation (typically, dechlorination) types of non-catalytic or (homogeneous or heterogeneous) catalytic, redox chemical reactions, phenomena, mechanisms, and processes, involving the use of (organic or/and inorganic) chemical reagents, for ‘chemically’ dehalogenating (dechlorinating) the halogenated organic compounds in the contaminated water. In general, reductive dehalogenation involves transfer of a number of electrons (ne⁻), either in the absence or presence of a catalyst (such as an electron transfer mediator type catalyst), from a bulk electron donor or reducing agent (being any of a wide variety and combinations of numerous possible organic or/and inorganic chemicals (for example, naturally existing in, originating from, or synthetically derived from, mineral matter, plant matter, or biological matter)), to an electron acceptor, being the halogenated (typically, chlorinated) organic compound contaminant ([R—X]; X=halogen, typically, chlorine [Cl]). The reductive dehalogenation chemical reaction is a form of (non-catalytic or catalytic) hydrogenolysis whose general scheme (without or with a catalyst) is indicated by chemical equation (1), wherein Y⁺ is a proton [H⁺] or any other positively charged atom or moiety:

R—X+ne ⁻+Y⁺→R—Y+X⁻  (I)

Phytochemical Reductive Dehalogenation for Treating or Remediating (Phytoremediating) Water Contaminated with Halogenated Organic Compounds:

A first exemplary type of reductive dehalogenation for treating or remediating water contaminated with halogenated organic compounds is based on phytochemistry (plant chemistry). Phytochemical types of reductive dehalogenation (typically, dechlorination) non-catalytic or catalytic redox chemical reactions, involving the use of aquatic or terrestrial plants or plant derived chemicals as the bulk electron donors or reducing agents, for ‘phytochemically’ dehalogenating (dechlorinating) or ‘phytodegrading’ various different kinds of halogenated organic compounds in contaminated or polluted water, have been well studied [e.g., 42-46]. However, such studies provide no explicit or implicit teaching about catalytically treating or remediating (phytoremediating) water contaminated or polluted with halogenated organic herbicides, in general, for example, halogenated organic herbicide members in the above illustratively described three halogenated organic herbicide groups (FIGS. 1, 2, and 3), and chlorinated organonitrogen herbicides (CONHs), in particular.

Zero Valent Metal (ZVM) Reductive Dehalogenation for Treating or Remediating Water Contaminated with Halogenated Organic Compounds:

A second exemplary type of reductive dehalogenation for treating or remediating water contaminated with halogenated organic compounds is based on the use of elemental metal or a zero valent metal (ZVM). The zero valent metal (ZVM) reductive dehalogenation (typically, dechlorination) technique is generally based on exposing water contaminated or polluted with halogenated organic compounds to a bulk quantity of (preferably nano-sized) granular or/and powdered elemental metal particles in the metallic or zero valent state, either in the absence or presence of an electron transfer mediator type catalyst, during which the contaminants are transformed, converted, or degraded, to non-hazardous or/and less hazardous compounds, or/and are immobilized on the surface of the metal particles, for example, by adsorption or/and precipitation processes. Typically, exposing the contaminated water to the zero valent metal particles is performed in a manner, for example, under reducing (anaerobic or anoxic) conditions, such that only contaminant species in the contaminated water, and not non-contaminant species (such as oxygen gas) in the contaminated water or/and in the immediate vicinity of the contaminated water, are reduced by the zero valent metal particles.

The exact mechanisms of zero valent metal (ZVM) reductive dehalogenation are not fully elucidated, but it appears that in general, a two-electron transfer occurs either directly on the metal surface, or/and through some intermediary (catalyst), in particular, depending upon the absence or presence of a catalyst, from the bulk electron donor or reducing agent (which becomes oxidized), to the halogenated organic compound contaminant ([R—X]; X=halogen, typically, chlorine [Cl]) as the electron acceptor, thereby reducing the halogenated organic compound contaminant, for example, to a reduced form [R—H], as generally indicated by chemical equation (2), wherein Y⁺ is a proton [H⁺] or any other positively charged atom or moiety:

R—X+M⁰+Y⁺→M²⁺+R—Y+X⁻  (2)

Although different elemental or zero valent metals, for example, iron [Fe⁰], cobalt [Co⁰], nickel [Ni⁰], copper [Cu⁰], and zinc [Zn⁰], are applicable, zero valent iron [Fe⁰] (ZVI) is most commonly used for implementing the ZVM technique. The zero valent metal reductive dehalogenation process has been known for years, however, only during the past decade has the use of ZVM, in general, and ZVI, in particular, become accepted as one of the most effective means of groundwater remediation. ZVI particles are relatively inexpensive, and reasonably effective for in-situ or ex-situ catalytically reducing concentrations of a wide variety of different types of groundwater contaminants, such as organic compounds, for example, halogenated organic compounds and degradation products thereof, and inorganic compounds, for example, oxo-anions, metals and metal ions, and radionuclides.

There are extensive prior art teachings [e.g., 47-54] about the ZVM technique, typically involving use of zero valent iron (ZVI) in non-catalytic reaction systems, for non-catalytically reductively dechlorinating chlorinated organic solvents, such as carbon tetrachloride (CT) [C(Cl)₄], dichloroethylene (dichloroethene) (DCE) [C₂H₂Cl₂], trichloroethylene (trichloroethene) (TCE) [C₂HCl₃], perchloroethylene (PCE) (tetrachloroethylene, tetrachloroethene) [C₂Cl₄], among many others, which are of significant environmental concern.

There are also prior art teachings about the ZVM technique, involving use of zero valent iron (ZVI) in non-catalytic reaction systems, for non-catalytically reductively dechlorinating atrazine [55, 56] and other triazine herbicides (terbutylazine (TBA), deisopropyl atrazine (DIA), and chlorinated dimethoxy triazine (CDMT) [57], as exemplary chlorinated organonitrogen herbicide (CONH) members in the chlorotriazine herbicide group (FIG. 1), in aqueous solutions.

However, no such prior art provides explicit or implicit teaching about (homogeneously or heterogeneously) catalytically treating or remediating water contaminated or polluted with halogenated organic herbicides, in general, for example, halogenated organic herbicide members in the above illustratively described three halogenated organic herbicide groups (FIGS. 1, 2, and 3), and chlorinated organonitrogen herbicides (CONHs), in particular.

Electron Transfer Mediators as Catalysts of Reductive Dehalogenation Reactions:

An active area in the field of environmental science and technology, focusing on treating or remediating water contaminated or polluted with halogenated organic compounds, concerns the use of electron transfer mediators for (homogeneously or heterogeneously) catalyzing reductive dehalogenation (typically, dechlorination) of halogenated organic compounds under reducing (typically, anaerobic or anoxic) conditions.

Electron transfer mediators are chemical substances, functioning as catalysts or co-catalysts, which are catalytically active, and expedite (catalyze) redox (reduction-oxidation) types of chemical reactions, such as reductive dehalogenation, by participating in, mediating, and expediting, the transfer of electrons from a bulk electron donor or reducing agent to an electron acceptor, or/and by stabilizing intermediate forms of the redox reactants. An electron transfer mediator which specifically functions by participating in, mediating, and expediting, the transfer of electrons from a bulk electron donor or reducing agent to an electron acceptor is also known as an electron carrier or as an electron shuttle, since electrons are carried and shuttled by such a chemical species.

Based on the above described general mechanism of reductive dehalogenation, along with reference to chemical equation (1), the general mechanism of an electron shuttle type of reductive dehalogenation system which includes an electron transfer mediator type catalyst is as follows. Under reducing conditions, in the presence of an electron transfer mediator type catalyst, the bulk electron donor or reducing agent transfers the electrons (ne⁻) to an electron transfer mediator molecule, which becomes reduced, during which the bulk electron donor or reducing agent becomes oxidized. The reduced electron transfer mediator molecule then carries (shuttles) and transfers the electrons to a halogenated organic compound contaminant [R—X] electron acceptor, which becomes reduced [R—Y], during which the electron transfer mediator molecule becomes oxidized. The oxidized electron transfer mediator molecule is then reduced again by the bulk electron donor or reducing agent, thus enabling the electron transfer mediated catalytic reductive dehalogenation cycle to repeat.

Numerous laboratory studies [e.g., 58-66] have shown that reductive transformation, conversion, or degradation, of certain relatively oxidized organic compounds (such as halogenated organic compounds) can be expedited (i.e., catalyzed) by use of electron transfer mediator type catalysts in electron shuttle systems. In general, electron shuttle systems involve the use of naturally occurring organic macrocycles complexed with transition metals, as electron transfer mediators, to carry and shuttle electrons from the bulk electron donor or reducing agent to the electron acceptor, thereby reductively transforming, converting, or degrading, the electron acceptor (halogenated organic compound). These relatively simple laboratory abiotic (but biomimetic) systems typically exhibit faster reaction rates relative to systems utilizing direct biological reduction reactions. Several naturally occurring biogeochemical substances, such as mineral substances, naturally occurring organic matter (NOM), bacterial transition metal coenzymes, and porphyrinogenic organometallic complexes, such as metalloporphyrins and metalloporphyrin-like complexes, and other biomimetic macrocycles, have been proposed and studied for use as electron transfer mediator type catalysts [e.g., 58, 64, 67-73].

Prior art includes various teachings of such electron transfer mediated catalytic reductive dehalogenation reaction systems, where the electron transfer mediator type catalyst is a humic substance [e.g., 74-76], a quinone [e.g., 77], or a protein [e.g., 78]. However, most such studies to date involve the use of a porphyrinogenic organometallic complex, such as a metalloporphyrin or a metalloporphyrin-like complex, as the electron transfer mediator type catalyst, in (homogeneous or heterogeneous) catalytic reaction systems, for catalytically reductively dehalogenating (typically, dechlorinating) halogenated organic compounds, particularly, halogenated organic solvents.

Porphyrinogenic Organometallic Complexes (Electron Transfer Mediator Catalytic Functionality):

The term ‘porphyrinogenic organometallic complex’ refers to an organometallic complex formed between a neutral metal atom or a metal ion and a porphyrinogenic or porphyrinogenic-like ring system, and is further defined and exemplified hereinbelow in the Description of the present invention.

Metalloporphyrin complexes (commonly known and referred to as metalloporphyrins), being porphyrinogenic organometallic complexes of metal ions and porphyrin ligands, are organic tetrapyrrole macrocycles composed of four pyrrole type rings joined by methane (methylidene) bridges and complexed to a central metal ion. They form a near planar structure of aromatic macrocycles containing up to 22 conjugated π electrons, 18 of which are incorporated into the delocalization pathway in accordance with Huckel's [4n+2] rule of aromaticity. One or two of the peripheral double bonds of the porphyrin ligands of a metalloporphyrin can undergo an addition reaction to form a metalloporphyrin derivative, such as a metallocorrin or a metallochlorin type of porphyrinogenic organometallic complex.

There are extensive teachings [e.g., 79] about the origin, and the numerous physical, chemical, and biological, properties, characteristics, and behavior, of porphyrinogenic organometallic complexes, of which thousands have been identified and studied [e.g., 80, 81]. Exemplary well known metalloporphyrin complexes are chlorophylls, which are magnesium (II) complexes, and hemes, which are iron (II) complexes. Vitamin B₁₂ (cyanocobalamin) a naturally occurring, or synthesized, metalloporphyrin-like complex of related structure and function, is a metallocorrin type of porphyrinogenic organometallic complex composed of a corrin ligand (a porphyrin analog in which some of the methylene bridges are substituted or/and absent) complexed to a cobalt (III) ion.

Porphyrinogenic organometallic complexes, such as metalloporphyrins, metalloporphyrin-like complexes, and their derivatives, exist in many biochemical environments, such as living cells, soils, sediments, bitumens, coal, oil shales, petroleum, and other types of naturally occurring deposits rich in organic matter [82-84]. Porphyrinogenic organometallic complexes are well known for functioning as electron transfer mediators, and play an important role in various biochemical pathways, such as oxygen transport and storage (hemoglobin and myoglobin, respectively) and electron transfer in redox (reduction-oxidation) reactions (cytochromes).

Porphyrinogenic organometallic complexes exhibit several particular properties, characteristics, and behavior, which make them especially well applicable for functioning as electron transfer mediator type catalysts in homogeneous or heterogeneous electron transfer mediated catalytic reductive dehalogenation (typically, dechlorination) reaction systems, for catalyzing reductive dehalogenation of halogenated organic compound contaminants in water under reducing (anaerobic or anoxic) conditions. Porphyrinogenic organometallic complexes are: (1) effective redox catalysts for many reactions, and have a long range of redox activity; (2) electrochemically active with almost any core metal; (3) active catalysts in aqueous solution under conditions pertinent to environments of various different forms of contaminated water, such as groundwater, surface water, above surface water, or a combination thereof; and (4) relatively highly stable, thereby enabling reactions to take place under severe conditions, where other types of reactions probably would not take place.

Porphyrinogenic organometallic complexes, such as metalloporphyrins and metalloporphyrin-like complexes, are well known for being used as electron transfer mediator type catalysts in homogeneous catalytic reduction processes. There are numerous prior art teachings [e.g., 58-66, 85-97] about electron transfer mediated homogeneous catalytic reductive dehalogenation (typically, dechlorination) reaction systems, involving the use of various different porphyrinogenic organometallic complexes as homogeneous electron transfer mediator type catalysts (i.e., an initially solid (typically, particulate) substance that is non-supported, non-matrixed, non-intercalated, or/and non-trapped, by another material, and subsequently becomes freely mobile and soluble throughout the contaminated water), for homogeneously catalyzing reductive dehalogenation of halogenated organic compounds, such as halogenated organic solvents or other non-herbicide type halogenated organic compounds, particularly those which are known problematic contaminants or pollutants in water. In the above cited prior art, halogenated (chlorinated) organic compounds most extensively and frequently studied are: chlorinated methanes, chlorinated ethanes, chlorinated ethylenes (ethenes), chlorinated phenols (chlorophenols), and polychlorinated biphenyls (PCBs).

There are also prior art teachings [46] of using hematin (reduced form of the porphyrin heme), or the metalloporphyrin hemoglobin, as an electron transfer mediator type catalyst, in the presence of dithionite (hydrosulfite) [S₂O₄ ⁻²] as a bulk electron donor or reducing agent, for homogeneous catalytic reductive dehalogenation (dechlorination) and degradation, in aqueous solutions, of various enantiomeric forms and analogs of the (bridged diphenyl) halogenated organic compound DDT (p,p′-DDT) (DichloroDiphenylTrichloroethane) [C₁₄H₉Cl₅]—well known for functioning as an insecticide, and as an acaricide or miticide (substances lethal to ticks and mites), and as being a proven extremely hazardous water contaminant or pollutant.

However, no such prior art provides explicit or implicit teaching about (homogeneously or heterogeneously) catalytically treating or remediating water contaminated or polluted with halogenated organic herbicides, in general, for example, halogenated organic herbicide members in the above illustratively described three halogenated organic herbicide groups (FIGS. 1, 2, and 3), and chlorinated organonitrogen herbicides (CONHs), in particular.

Electron Transfer Mediators as Catalysts in Heterogeneous Composites, for Reductive Dehalogenation:

Studies have shown that porphyrinogenic organometallic complexes, such as metalloporphyrins, can be incorporated (via intercalation) and immobilized on or/and in layered minerals, or amorphous silica gel surfaces, for forming heterogeneous composites that can be used for heterogeneously catalyzing electron transfer mediated reactions. For example, heterogeneous composites composed of the cobalt metalloporphyrin, tetramethylpyridilporphyrin [5,10,15,20-tetrakis(1-methyl-4-pyridinio)-porphine-cobalt] [TMPyP-Co], incorporated on or/and in silica gel and double-layered clays were used for heterogeneously catalyzing reductive dechlorination of carbon tetrachloride [CCl₄] in water [98]. Prior art [e.g., 99] also includes teachings about incorporating and immobilizing metalloporphyrins on or/and in sepharose, sephadex, or polystyrene, types of solid support or matrix materials, for forming heterogeneous composites that can be used for heterogeneously catalyzing electron transfer mediated reductive dechlorination reactions.

Based on, and further extending, prior art teachings [e.g., 47-57] about the ZVM technique, involving use of a zero valent metal in non-catalytic reaction systems, for non-catalytically reductively dechlorinating chlorinated organic compounds, along with prior art teachings [e.g., 46, 58-66, 85-97] about electron transfer mediators, such as porphyrinogenic organometallic complexes, functioning as effective catalysts in homogeneous catalytic reaction systems, for homogeneously catalytically reductively dechlorinating chlorinated organic compounds, combined with prior art teachings [e.g., 98, 99] about immobilized porphyrinogenic organometallic complex types of electron transfer mediators functioning as effective catalysts included in various different types of heterogeneous composites, for heterogeneously catalytically reductively dechlorinating chlorinated organic compounds, led the current assignee/applicant to propose and reduce to practice the inventive concept of incorporating a porphyrinogenic organometallic complex type of electron transfer mediator functioning as a catalyst, and zero valent metal (ZVM) nanometer sized particles, on or/and into a powdered diatomite (kieselguhr) support or matrix (optionally, including vermiculite), for forming a diatomite/zero valent metal (ZVM)/electron transfer mediator composite type of heterogeneous catalyst, for heterogeneously catalyzing reductive dehalogenation (especially, dechlorination) reactions, which can be applied for catalytically treating or remediating contaminated or polluted water which includes, for example, halogenated organic compounds, particularly, halogenated organic solvents, such as chlorinated organic solvents.

Recently, in PCT Int'l. Pat. Appl. Pub. No. WO 2006/072944, published Jul. 13, 2006, the current assignee/applicant described the inventive diatomite/ZVM/electron transfer mediator composite, a method for manufacturing thereof, a method using thereof, and a system including thereof, for (in-situ or ex-situ) heterogeneously catalytically treating contaminated water, wherein the contaminated water is a form of groundwater, surface water, above surface water, vapor, or/and gas. In the composite, exemplary zero valent metals (functioning as a bulk electron donor or reducing agent) are zero valent transition metals, such as zero valent iron, cobalt, nickel, copper, or/and zinc. Preferably, the electron transfer mediator (functioning as the main catalytically active component of the heterogeneous composite) is a porphyrinogenic organometallic complex, such as a metalloporphyrin, for example, a chlorophyll (magnesium (II) complex) or a heme (iron (II) complex), or/and, a metalloporphyrin-like complex, for example, the metallocorrin type of organometallic complex, vitamin B₁₂ (cyanocobalamin) (corrin ligand (a porphyrin analog) complexed to a cobalt (III) ion). For implementation, the heterogeneous composite is dispersed throughout the contaminated water under reducing (typically, anaerobic or anoxic) conditions.

The diatomite/ZVM/electron transfer mediator composite heterogeneous catalytic system can generally be described by a cyclical type of heterogeneous catalytic redox reaction mechanism. With reference to chemical equation (2), above, under reducing (typically, anaerobic or anoxic) conditions, in the presence of an electron transfer mediator (as the main catalytically active component of the composite heterogeneous catalyst), a zero valent metal atom [M⁰] as the bulk electron donor or reducing agent transfers electrons, for example, two electrons, to an electron transfer mediator molecule, which becomes reduced, during which the zero valent metal atom is oxidized to a metal ion, for example, metal(II) ion [M²⁺]. The reduced electron transfer mediator molecule then carries (shuttles) and transfers the electrons to a halogenated organic compound contaminant [R—X] electron acceptor, which becomes reduced [R—Y], during which the electron transfer mediator molecule becomes oxidized. The oxidized electron transfer mediator molecule is then reduced again by another zero valent metal atom [M⁰] bulk electron donor or reducing agent, thus enabling the electron transfer mediated catalytic zero valent metal (ZVM) reductive dehalogenation cycle to repeat.

Nevertheless, the above described extensive amount of prior teachings about non-catalytic reductive dehalogenation (typically, dechlorination) reaction systems, and about electron transfer mediated (homogeneous or heterogeneous) catalytic reductive dehalogenation (typically, dechlorination) reaction systems, involving the use of various different porphyrinogenic organometallic complexes as electron transfer mediator type catalysts, for homogeneously or heterogeneously catalyzing reductive dehalogenation of halogenated organic compounds, such as halogenated organic solvents or other non-herbicide type halogenated organic compounds, provides no explicit or implicit teaching about (homogeneously or heterogeneously) catalytically treating or remediating water contaminated or polluted with halogenated organic herbicides, in general, for example, halogenated organic herbicide members in the above illustratively described three halogenated organic herbicide groups (FIGS. 1, 2, and 3), and chlorinated organonitrogen herbicides (CONHs), in particular.

More generally, currently known non-catalytic reductive dehalogenation (typically, dechlorination) reaction systems, or electron transfer mediated (homogeneous or heterogeneous) catalytic reductive dehalogenation (typically, dechlorination) reaction systems, are ordinarily not technologically or/and economically feasible or viable for treating or remediating water contaminated or polluted with halogenated organic herbicides.

Accordingly, new, technologically and economically feasible, and effective treatment and remediation techniques need to be developed and implemented in order to meet stringent water quality standards, and to reduce environmental and health risks associated with halogenated organic herbicides, in general, and CONHs, in particular, and their degradation products, present in, or in close proximity to, forms of water which either are, or lead to, sources of water to which humans or/and animals are directly or indirectly exposed.

There is thus a need for, and it would be highly advantageous to have a method of catalytically treating water contaminated with halogenated organic compounds, and a system thereof, wherein the halogenated organic compounds are selected from the group consisting of chlorotriazine herbicides, chloroacetanilide herbicides, halogenated aliphatic herbicides, halogen containing analogs thereof, halogen containing derivatives thereof, and combinations thereof. There is a need for such an invention which is applicable for (in-situ or/and ex-situ) homogeneously or heterogeneously catalytically treating contaminated water being a variety of different forms, such as groundwater (e.g., sub-surface water regions, reservoirs, or aquifers), surface water (e.g., rivers, lakes, ponds, pools, or surface water reservoirs), above surface water (e.g., above surface water reservoirs, or above surface sources or supplies of residential or commercial drinking water), or a combination thereof. Moreover, there is a need for such an invention which is technologically and economically feasible, and effective for treating the contaminated water, to an extent that would allow continued use of the indicated halogenated organic herbicides in the field of agriculture without adversely affecting the environment.

SUMMARY OF THE INVENTION

The present invention relates to a method of catalytically treating water contaminated with halogenated organic compounds, and a system thereof, wherein the halogenated organic compounds are selected from the group consisting of chlorotriazine herbicides, chloroacetanilide herbicides, halogenated aliphatic herbicides, halogen containing analogs thereof, halogen containing derivatives thereof, and combinations thereof. These herbicide type halogenated organic compounds, at room temperature (between about 20° C. and about 25° C.) and atmospheric pressure, are non-volatile particulate substances (nearly all) or liquids (some) which, at typical contaminant concentrations (e.g., ppb-ppm range) are mobile and soluble in water, and are of particular interest in the field of environmental science and technology focusing on treating or remediating contaminated or polluted water. The present invention is applicable for (in-situ or/and ex-situ) homogeneously or/and heterogeneously catalytically treating such contaminated water being a variety of different forms, such as groundwater (e.g., sub-surface water regions, reservoirs, or aquifers), surface water (e.g., rivers, lakes, ponds, pools, or surface water reservoirs), above surface water (e.g., above surface water reservoirs, or above surface sources or supplies of residential or commercial drinking water), or a combination thereof.

The method of catalytically treating water contaminated with halogenated organic compounds, wherein the halogenated organic compounds are selected from the group consisting of chlorotriazine herbicides, chloroacetanilide herbicides, halogenated aliphatic herbicides, halogen containing analogs thereof, halogen containing derivatives thereof, and combinations thereof, of the present invention, includes the main procedure of exposing the contaminated water to a catalytically effective amount of at least one electron transfer mediator under reducing conditions, to thereby decrease the concentration of at least one of the halogenated organic compounds in the contaminated water.

The system for catalytically treating water contaminated with halogenated organic compounds, wherein the halogenated organic compounds are selected from the group consisting of chlorotriazine herbicides, chloroacetanilide herbicides, halogenated aliphatic herbicides, halogen containing analogs thereof, halogen containing derivatives thereof, and combinations thereof, of the present invention, includes the following main components and functionalities thereof: (a) at least one electron transfer mediator; and (b) at least one (in-situ or/and ex-situ) unit for containing a catalytically effective amount of the at least one electron transfer mediator, for exposing the contaminated water to the at least one electron transfer mediator under reducing conditions.

The method and system of the present invention are based on using a chemical technique for catalytically treating the contaminated water, by exploiting catalytic chemical reaction types of phenomena, mechanisms, and processes, involving the use of at least one electron transfer mediator functioning as an active redox catalyst under reducing (typically, anaerobic or anoxic) conditions, for in-situ or/and ex-situ, homogeneously or/and heterogeneously, catalytically degrading, transforming, or converting, in particular, via reductive dehalogenation (typically, dechlorination) of, the halogenated organic compounds in the contaminated water to non-hazardous or/and less hazardous (poisonous or toxic) chemical species. Implementation of the present invention results in decreasing the concentration of at least one of the halogenated organic compounds in the contaminated water.

In general, essentially any electron transfer mediator functioning as an active redox catalyst under reducing (anaerobic or anoxic) conditions can be used for implementing the method and system of the present invention. Preferably, the at least one electron transfer mediator is selected from the group consisting of a porphyrinogenic organometallic complex, an analog thereof, a derivative thereof, and any combination thereof. Preferably, the at least one porphyrinogenic organometallic complex is selected from the group consisting of a metalloporphyrin complex, a metallocorrin complex, a metallochlorin complex, and any combination thereof.

Preferably, the metalloporphyrin complex is composed of a transition metal complexed to a porphyrin selected from the group consisting of:

-   tetramethylpyridilporphyrin     [5,10,15,20-tetrakis(1-methyl-4-pyridinio)-porphine] [TMPyP]; -   tetrahydroxyphenylporphyrine     [5,10,15,20-tetrakis(4-hydroxyphenyl)-21H,23H-porphine] [TP(OH)P]; -   tetraphenylporphyrin [5,10,15,20-tetraphenyl-21H,23H-porphine]     [TPP]; and -   4,4′,4″,4″′-(porphine-5,10,15,20-tetrayl)tetrakis(benzenesulfonic     acid) [TBSP].

The transition metal is essentially any transition metal capable of complexing with the just stated porphyrins for forming the corresponding metalloporphyrin complex. Preferably, the transition metal is selected from the group consisting of cobalt [Co], nickel [Ni], iron [Fe], zinc [Zn], and copper [Cu].

Accordingly, for implementing the present invention, preferred metalloporphyrin complexes are:

-   tetramethylpyridilporphyrin-transition metal     [5,10,15,20-tetrakis(1-methyl-4-pyridinio)-porphine-transition     metal] [TMPyP-transition metal];

tetrahydroxyphenylporphyrine-transition metal [5,10,15,20-tetrakis(4-hydroxyphenyl)-21H,23H-porphine-transition metal] [TP(OH)P-transition metal];

-   tetraphenylporphyrin-transition metal     [5,10,15,20-tetraphenyl-21H,23H-porphine-transition metal]     [TPP-transition metal]; and -   4,4′,4″,4″′-(porphine-5,10,15,20-tetrayl)tetrakis(benzenesulfonic     acid)transition metal [TBSP-transition metal],

where, in each metalloporphyrin complex the transition metal is cobalt [Co], nickel [Ni], iron [Fe], zinc [Zn], or copper [Cu].

Additional exemplary metalloporphyrin complexes which are suitable for implementing the present invention are selected from the group consisting of chlorophylls [magnesium (II) complexes], and hemes [iron (II) complexes]. An exemplary metallocorrin complex which is suitable for implementing the present invention is vitamin B₁₂ [corrin ligand (porphyrin analog) complexed to a cobalt (III) ion].

Catalytically treating the contaminated water, involving catalytic degradation, transformation, or conversion, of the halogenated organic compounds in the contaminated water to non-hazardous or/and less hazardous chemical species, thereby decreasing the concentration of at least one of the halogenated organic compounds in the contaminated water, is effected according to homogeneous catalysis or/and according to heterogeneous catalysis, under reducing (anaerobic or anoxic) conditions. According to homogeneous catalysis, the catalytically effective amount of the at least one electron transfer mediator (catalyst) is an initially solid (typically, particulate) substance that is non-supported, non-matrixed, non-intercalated, or/and non-trapped, by another material, and subsequently becomes freely mobile and soluble throughout the contaminated water. According to heterogeneous catalysis, the catalytically effective amount of the at least one electron transfer mediator (catalyst) is an initially solid (typically, particulate) substance that is supported, matrixed, intercalated, incorporated, or/and trapped, and generally immobile, on or/and inside of a (particulate or/and non-particulate) solid support or matrix material which subsequently becomes dispersed (i.e., not dissolved) throughout the contaminated water. Ordinarily, the initially immobilized catalytically effective amount of the at least one electron transfer mediator (catalyst) similarly becomes dispersed (i.e., not dissolved) throughout the contaminated water. However, any one or more immobilized electron transfer mediator may at least partially dissolve in the contaminated water, depending upon actual parameters and conditions of a given heterogeneous catalytic chemical reaction system during implementation of the present invention.

For implementing the present invention according to heterogeneous catalysis, in general, essentially any type of heterogeneous catalyst (preferably, but not limited to being, particulate) solid support or matrix material can be used for supporting, matrixing, and immobilizing, the at least one electron transfer mediator (catalyst). Exemplary types of suitable (particulate or/and non-particulate) solid support or matrix materials are diatomite (kieselguhr), amorphous silicas, crystalline silicas, silica gels, aluminas, minerals, ceramics, carbohydrates (such as sepharose, sephadex), clays, plastics (such as polystyrene), composites, and combinations thereof.

A specific example of such an electron transfer mediator solid supported or matrixed configuration is a diatomite/zero valent metal (ZVM)/electron transfer mediator composite type of heterogeneous catalyst, composed of a powdered diatomite (kieselguhr) support or matrix (optionally, including vermiculite) on or/and into which are incorporated at least one (preferably, porphyrinogenic organometallic complex type of) electron transfer mediator functioning as a catalyst, and zero valent metal (ZVM) nanometer sized particles, for example, having a size in a range of between about 5 nm and about 600 nm, functioning as a bulk electron donor or reducing agent, as described by the present assignee/applicant in PCT Int'l. Pat. Appl. Pub. No. WO 2006/072944, published Jul. 13, 2006, entitled: “Zero Valent Metal Composite Catalyst, Manufacturing, System And Method Using Thereof, For Catalytically Treating Contaminated Water”.

Exposing the contaminated water to the catalytically effective amount of the at least one electron transfer mediator is performed, for example, according to homogeneous catalysis or according to heterogeneous catalysis, each via a batch mode, or, alternatively, each via a flow mode, for forming a respective homogeneous or heterogeneous catalytic reaction system of either mode, under reducing (anaerobic or anoxic) conditions, i.e., when reducing conditions, as opposed to oxidizing conditions, are prevalent in the contaminated water. According to homogeneous catalysis, via a batch or flow mode, either part of, or the entire, catalytically effective amount of the at least one electron transfer mediator is used ‘as is’, in a particulate form, i.e., as a generally dry, single particulate substance or mixture of several particulate substances. Alternatively, or additionally, prior to exposure to the contaminated water, either part of, or the entire, catalytically effective amount of the at least one electron transfer mediator is dissolved in one or more suitable (aqueous or/and organic) solvents at suitable conditions (temperature, pH, mixing), and then used in a solution form, i.e., as a solution of a dissolved single particulate substance or as a solution of a dissolved mixture of several particulate substances. According to heterogeneous catalysis, via a batch or flow mode, ordinarily, the entire catalytically effective amount of the at least one electron transfer mediator is used ‘as is’, in a particulate form, i.e., as a generally dry, single particulate substance or mixture of several particulate substances, of one or more electron transfer mediator solid supported or matrixed configurations.

Reducing conditions naturally exist, or/and are anthropogenically (human) produced, in the contaminated water. When reducing conditions are not present in the contaminated water, or are considered insufficient for effectively enabling the phenomena, mechanisms, and processes, of the electron transfer mediated (homogeneous or heterogeneous) catalytic reductive dehalogenation reactions, for catalyzing reductive dehalogenation of the halogenated organic compound contaminants in the contaminated water, then, there is need for anthropogenically producing the reducing conditions in the contaminated water.

Anthropogenically producing the reducing conditions in the contaminated water is performed by exposing the contaminated water to at least one bulk electron donor or reducing agent, immediately before, or/and during, or/and immediately after, exposing the contaminated water to the catalytically effective amount of the at least one electron transfer mediator. Alternatively, anthropogenically producing the reducing conditions in the contaminated water is performed by using an electron transfer mediator solid supported or matrixed configuration type of heterogeneous catalyst that already includes at least one bulk electron donor or reducing agent as part of the heterogeneous catalyst structure or composition.

In general, essentially any bulk electron donor or reducing agent capable of reducing an electron transfer mediator under reducing (anaerobic or anoxic) conditions can be used for implementing the present invention. Preferably, the at least one bulk electron donor or reducing agent includes an elemental metal (zero valent metal). Preferably, the bulk electron donor or reducing agent elemental metal (zero valent metal) is selected from the group consisting of iron [Fe], lithium [Li], sodium [Na], potassium [K], beryllium [Be], magnesium [Mg], titanium [Ti], and any mixture thereof. Alternatively, the bulk electron donor or reducing agent is selected from the group consisting of titanium citrate [Ti(OC(CH₂COOH)₂COOH], potassium borohydride [KBH₄], sodium borohydride [NaBH₄], lithium hydride [LiH], potassium hydride [KaH], sodium hydride [NaH], borotrihydride [BH₃], aluminum trihydride [AlH₃], hydrazine [H₂NNH₂], triphenylphosphate [PPh₃], sodium dithionite (sodium hydrosulfite) [Na₂S₂O₄], and any combination thereof.

In general, for implementing the present invention, the extent of time or duration (for example, hours, days, weeks, etc.) of exposing the contaminated water to the catalytically effective amount of the at least one electron transfer mediator, under reducing conditions, depends upon a variety of parameters and conditions of a given batch or flow mode homogeneous or heterogeneous catalytic reaction system.

For implementing the present invention, exemplary applicable in-situ units for containing the catalytically effective amount of the at least one electron transfer mediator as a heterogeneous catalyst are either in a form as at least part of a groundwater permeable reactive barrier (PRB) configured as a continuous filled in trench or wall, or as a stand-alone filled in well, or, in a form as part of a groundwater pumping and treatment system. An exemplary applicable ex-situ unit for containing the catalytically effective amount of the at least one electron transfer mediator as a homogeneous catalyst or/and as a heterogeneous catalyst is in a form as part of an above surface water treatment reactor system.

Following heterogeneous catalytic treatment of the contaminated water, an electron transfer mediator solid supported or matrixed configuration type heterogeneous catalyst can be removed from a given in-situ or ex-situ unit used for treating the contaminated water, and be recycled for again treating the contaminated water. Such recycling can include, for example, subjecting the electron transfer mediator solid supported or matrixed configuration type heterogeneous catalyst to a cleaning procedure, involving selective removal of the adsorbed contaminants from the solid support or matrix, while non-destructively handling and processing the solid support or matrix.

The present invention is particularly applicable for catalytically treating water contaminated with halogenated organic compounds, wherein the halogenated organic compounds are selected from the group consisting of chlorotriazine herbicides, chloroacetanilide herbicides, halogenated aliphatic herbicides, halogen containing analogs thereof, halogen containing derivatives thereof, and combinations thereof. Nevertheless, the method and system of the present invention are generally applicable for catalytically treating water contaminated with other types or kinds of halogenated organic compounds, not limited to being halogenated organic herbicides, halogen containing analogs thereof, or halogen containing derivatives thereof.

Thus, according to the present invention, there is provided a method of catalytically treating water contaminated with halogenated organic compounds, wherein the halogenated organic compounds are selected from the group consisting of chlorotriazine herbicides, chloroacetanilide herbicides, halogenated aliphatic herbicides, halogenated analogs thereof, halogenated derivatives thereof, and combinations thereof, the method comprising exposing the contaminated water to a catalytically effective amount of at least one electron transfer mediator under reducing conditions, to thereby decrease concentration of at least one of the halogenated organic compounds in the contaminated water.

According to another aspect of the present invention, there is provided a system for catalytically treating water contaminated with halogenated organic compounds, wherein the halogenated organic compounds are selected from the group consisting of chlorotriazine herbicides, chloroacetanilide herbicides, halogenated aliphatic herbicides, halogenated analogs thereof, halogenated derivatives thereof, and combinations thereof, of the present invention, includes the following main components and functionalities thereof: (a) at least one electron transfer mediator; and (b) at least one (in-situ or/and ex-situ) unit for containing a catalytically effective amount of the at least one electron transfer mediator, for exposing the contaminated water to the at least one electron transfer mediator under reducing conditions.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is herein described, by way of example only, with reference to the accompanying drawings. With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative description of the preferred embodiments of the present invention only, and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the present invention. In this regard, no attempt is made to show structural details of the present invention in more detail than is necessary for a fundamental understanding of the invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the invention may be embodied in practice. In the drawings:

FIG. 1 is a table listing the compound common name, chemical formula, and CAS number, and showing the structure, of known members in the chlorotriazine herbicide group, which are within the scope of application of the present invention;

FIG. 2 is a table listing the compound common name, chemical formula, and CAS number, and showing the structure, of known members in the chloroacetanilide herbicide group, which are within the scope of application of the present invention;

FIG. 3 is a table listing the compound common name, chemical formula, and CAS number, and showing the structure, of known members in the halogenated aliphatic herbicide group, which are within the scope of application of the present invention;

FIG. 4 is a schematic diagram illustrating a cut-away view of exemplary specific preferred embodiments of implementing the method and system of the present invention according to heterogeneous catalysis, via a flow mode, wherein the contaminated water is in the form of a natural flow of groundwater, and the catalytically effective amount of the at least one electron transfer mediator (as a heterogeneous catalyst) is part of a (particulate or/and non-particulate) solid support or matrix material dispersed throughout and contained within an in-situ unit being in a form as the lower portion of a groundwater permeable reactive barrier (PRB) configured as a continuous filled in trench or wall, in accordance with the present invention;

FIG. 5 is a schematic diagram illustrating a cut-away view of exemplary specific preferred embodiments of implementing the method and system of the present invention according to heterogeneous catalysis, via a flow mode, wherein the contaminated water is in the form of a natural flow of groundwater, and the catalytically effective amount of the at least one electron transfer mediator (as a heterogeneous catalyst) is part of a (particulate or/and non-particulate) solid support or matrix material dispersed throughout and contained within each of a plurality of in-situ units each being in a form as a groundwater permeable reactive barrier (PRB) configured as a stand-alone filled in well, in accordance with the present invention;

FIG. 6 is a schematic diagram illustrating a cut-away view of exemplary specific preferred embodiments of implementing the method and system of the present invention according to heterogeneous catalysis, via a flow mode, wherein the contaminated water is in the form of a natural flow of groundwater, and the catalytically effective amount of the at least one electron transfer mediator (as a heterogeneous catalyst) is part of a (particulate or/and non-particulate) solid support or matrix material dispersed throughout and contained within an in-situ unit being in a form as part of a groundwater pumping and treatment system, in accordance with the present invention; and

FIG. 7 is a schematic diagram illustrating a cut-away view of three exemplary specific configurations, of exemplary specific preferred embodiments of implementing the method and system of the present invention according to homogeneous or/and heterogeneous catalysis, via a batch or flow mode, wherein the contaminated water is in the form(s) of (natural or/and forced) flow of groundwater, surface water, or/and above surface water, and the catalytically effective amount of the at least one electron transfer mediator is a homogeneous catalyst in a water soluble particulate form or/and aqueous solution form contained within an ex-situ unit, or/and is a heterogeneous catalyst as part of a (particulate or/and non-particulate) solid support or matrix material dispersed throughout and contained within an ex-situ unit, wherein the ex-situ unit is in a form as part of an above surface water treatment reactor system, in accordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention relates to a method of catalytically treating water contaminated with halogenated organic compounds, and a system thereof, wherein the halogenated organic compounds are selected from the group consisting of chlorotriazine herbicides, chloroacetanilide herbicides, halogenated aliphatic herbicides, halogen containing analogs thereof, halogen containing derivatives thereof, and combinations thereof. These herbicide type halogenated organic compounds, at room temperature (between about 20° C. and about 25° C.) and atmospheric pressure, are non-volatile particulate substances (nearly all) or liquids (some) which, at typical contaminant concentrations (e.g., ppb-ppm range) are mobile and soluble in water, and are of particular interest in the field of environmental science and technology focusing on treating or remediating contaminated or polluted water. The present invention is applicable for (in-situ or/and ex-situ) homogeneously or/and heterogeneously catalytically treating such contaminated water being a variety of different forms, such as groundwater (e.g., sub-surface water regions, reservoirs, or aquifers), surface water (e.g., rivers, lakes, ponds, pools, or surface water reservoirs), above surface water (e.g., above surface water reservoirs, or above surface sources or supplies of residential or commercial drinking water), or a combination thereof.

The method of catalytically treating water contaminated with halogenated organic compounds, wherein the halogenated organic compounds are selected from the group consisting of chlorotriazine herbicides, chloroacetanilide herbicides, halogenated aliphatic herbicides, halogen containing analogs thereof, halogen containing derivatives thereof, and combinations thereof, of the present invention, includes the main procedure of exposing the contaminated water to a catalytically effective amount of at least one electron transfer mediator under reducing conditions, to thereby decrease the concentration of at least one of the halogenated organic compounds in the contaminated water.

The system for catalytically treating water contaminated with halogenated organic compounds, wherein the halogenated organic compounds are selected from the group consisting of chlorotriazine herbicides, chloroacetanilide herbicides, halogenated aliphatic herbicides, halogen containing analogs thereof, halogen containing derivatives thereof, and combinations thereof, of the present invention, includes the following main components and functionalities thereof: (a) at least one electron transfer mediator; and (b) at least one (in-situ or/and ex-situ) unit for containing a catalytically effective amount of the at least one electron transfer mediator, for exposing the contaminated water to the at least one electron transfer mediator under reducing conditions.

The method and system of the present invention are based on using a chemical technique for catalytically treating the contaminated water, by exploiting catalytic chemical reaction types of phenomena, mechanisms, and processes, involving the use of at least one electron transfer mediator functioning as an active redox catalyst under reducing (typically, anaerobic or anoxic) conditions, for in-situ or/and ex-situ, homogeneously or/and heterogeneously, catalytically degrading, transforming, or converting, in particular, via reductive dehalogenation (typically, dechlorination) of, the halogenated organic compounds in the contaminated water to non-hazardous or/and less hazardous (poisonous or toxic) chemical species. Implementation of the present invention results in decreasing the concentration of at least one of the halogenated organic compounds in the contaminated water.

In general, essentially any electron transfer mediator functioning as an active redox catalyst under reducing (anaerobic or anoxic) conditions can be used for implementing the method and system of the present invention. Preferably, the at least one electron transfer mediator is selected from the group consisting of a porphyrinogenic organometallic complex, an analog thereof, a derivative thereof, and any combination thereof. Preferably, the at least one porphyrinogenic organometallic complex is selected from the group consisting of a metalloporphyrin complex, a metallocorrin complex, a metallochlorin complex, and any combination thereof.

Preferably, the metalloporphyrin complex is composed of a transition metal complexed to a porphyrin selected from the group consisting of:

-   tetramethylpyridilporphyrin     [5,10,15,20-tetrakis(1-methyl-4-pyridinio)-porphine] [TMPyP]; -   tetrahydroxyphenylporphyrine[5,10,15,20-tetrakis(4-hydroxyphenyl)-21H,23H-porphine]     [TP(OH)P]; -   tetraphenylporphyrin [5,10,15,20-tetraphenyl-21H,23H-porphine]     [TPP]; and -   4,4′,4″,4″′-(porphine-5,10,15,20-tetrayl)tetrakis(benzenesulfonic     acid) [TBSP].

The transition metal is essentially any transition metal capable of complexing with the just stated porphyrins for forming the corresponding metalloporphyrin complex. Preferably, the transition metal is selected from the group consisting of cobalt [Co], nickel [Ni], iron [Fe], zinc [Zn], and copper [Cu].

Additional exemplary metalloporphyrin complexes which are suitable for implementing the present invention are selected from the group consisting of chlorophylls [magnesium (II) complexes], and hemes [iron (II) complexes]. An exemplary metallocorrin complex which is suitable for implementing the present invention is vitamin B₁₂ [corrin ligand (porphyrin analog) complexed to a cobalt (III) ion].

Catalytically treating the contaminated water, involving catalytic degradation, transformation, or conversion, of the halogenated organic compounds in the contaminated water to non-hazardous or/and less hazardous chemical species, thereby decreasing the concentration of at least one of the halogenated organic compounds in the contaminated water, is effected according to homogeneous catalysis or/and according to heterogeneous catalysis, under reducing (anaerobic or anoxic) conditions. According to homogeneous catalysis, the catalytically effective amount of the at least one electron transfer mediator (catalyst) is an initially solid (typically, particulate) particulate substance that is non-supported, non-matrixed, non-intercalated, or/and non-trapped, by another material, and subsequently becomes freely mobile and soluble throughout the contaminated water. According to heterogeneous catalysis, the catalytically effective amount of the at least one electron transfer mediator (catalyst) is an initially solid (typically, particulate) substance that is supported, matrixed, intercalated, incorporated, or/and trapped, and generally immobile, on or/and inside of a (particulate or/and non-particulate) solid support or matrix material which subsequently becomes dispersed (i.e., not dissolved) throughout the contaminated water. Ordinarily, the initially immobilized catalytically effective amount of the at least one electron transfer mediator (catalyst) similarly becomes dispersed (i.e., not dissolved) throughout the contaminated water. However, any one or more immobilized electron transfer mediator may at least partially dissolve in the contaminated water, depending upon actual parameters and conditions of a given heterogeneous catalytic chemical reaction system during implementation of the present invention.

For implementing the present invention according to heterogeneous catalysis, in general, essentially any type of heterogeneous catalyst (preferably, but not limited to being, particulate) solid support or matrix material can be used for supporting, matrixing, and immobilizing, the at least one electron transfer mediator (catalyst). Exemplary types of suitable (particulate or/and non-particulate) solid support or matrix materials are diatomite (kieselguhr), amorphous silicas, crystalline silicas, silica gels, aluminas, minerals, ceramics, carbohydrates (such as sepharose, sephadex), clays, plastics (such as polystyrene), composites, and combinations thereof.

A specific example of such an electron transfer mediator solid supported or matrixed configuration is a diatomite/zero valent metal (ZVM)/electron transfer mediator composite type of heterogeneous catalyst, composed of a powdered diatomite (kieselguhr) support or matrix (optionally, including vermiculite) on or/and into which are incorporated at least one (preferably, porphyrinogenic organometallic complex type of) electron transfer mediator functioning as a catalyst, and zero valent metal (ZVM) nanometer sized particles, for example, having a size in a range of between about 5 nm and about 600 nm, functioning as a bulk electron donor or reducing agent.

Exposing the contaminated water to the catalytically effective amount of the at least one electron transfer mediator is performed, for example, according to homogeneous catalysis or according to heterogeneous catalysis, each via a batch mode, or, alternatively, each via a flow mode, for forming a respective homogeneous or heterogeneous catalytic reaction system of either mode, under reducing (anaerobic or anoxic) conditions, i.e., when reducing conditions, as opposed to oxidizing conditions, are prevalent in the contaminated water. According to homogeneous catalysis, via a batch or flow mode, either part of, or the entire, catalytically effective amount of the at least one electron transfer mediator is used ‘as is’, in a particulate form, i.e., as a generally dry, single particulate substance or mixture of several particulate substances. Alternatively, or additionally, prior to exposure to the contaminated water, either part of, or the entire, catalytically effective amount of the at least one electron transfer mediator is dissolved in one or more suitable (aqueous or/and organic) solvents at suitable conditions (temperature, pH, mixing), and then used in a solution form, i.e., as a solution of a dissolved single particulate substance or as a solution of a dissolved mixture of several particulate substances. According to heterogeneous catalysis, via a batch or flow mode, ordinarily, the entire catalytically effective amount of the at least one electron transfer mediator is used ‘as is’, in a particulate form, i.e., as a generally dry, single particulate substance or mixture of several particulate substances, of one or more electron transfer mediator solid supported or matrixed configurations.

Reducing conditions naturally exist, or/and are anthropogenically (human) produced, in the contaminated water. When reducing conditions are not present in the contaminated water, or are considered insufficient for effectively enabling the phenomena, mechanisms, and processes, of the electron transfer mediated (homogeneous or heterogeneous) catalytic reductive dehalogenation reactions, for catalyzing reductive dehalogenation of the halogenated organic compound contaminants in the contaminated water, then, there is need for anthropogenically producing the reducing conditions in the contaminated water.

Anthropogenically producing the reducing conditions in the contaminated water is performed by exposing the contaminated water to at least one bulk electron donor or reducing agent, immediately before, or/and during, or/and immediately after, exposing the contaminated water to the catalytically effective amount of the at least one electron transfer mediator. Alternatively, anthropogenically producing the reducing conditions in the contaminated water is performed by using an electron transfer mediator solid supported or matrixed configuration type of heterogeneous catalyst that already includes at least one bulk electron donor or reducing agent as part of the heterogeneous catalyst structure or composition.

In general, essentially any bulk electron donor or reducing agent capable of reducing an electron transfer mediator under reducing (anaerobic or anoxic) conditions can be used for implementing the present invention. Preferably, the at least one bulk electron donor or reducing agent includes an elemental metal (zero valent metal). Preferably, the bulk electron donor or reducing agent elemental metal (zero valent metal) is selected from the group consisting of iron [Fe], lithium [Li], sodium [Na], potassium [K], beryllium [Be], magnesium [Mg], titanium [Ti], and any mixture thereof. Alternatively, the bulk electron donor or reducing agent compounds is selected from the group consisting of titanium citrate [Ti(OC(CH₂COOH)₂COOH], potassium borohydride [KBH₄], sodium borohydride [NaBH₄], lithium hydride [LiH], potassium hydride [KaH], sodium hydride [NaH], borotrihydride [BH₃], aluminum trihydride [AlH₃], hydrazine [H₂NNH₂], triphenylphosphate [PPh₃], sodium dithionite (sodium hydrosulfite) [Na₂S₂O₄], and any combination thereof.

In general, for implementing the present invention, the extent of time or duration (for example, hours, days, weeks, etc.) of exposing the contaminated water to the catalytically effective amount of the at least one electron transfer mediator, under reducing conditions, depends upon a variety of parameters and conditions of a given batch or flow mode homogeneous or heterogeneous catalytic reaction system.

For implementing the present invention, exemplary applicable in-situ units for containing the catalytically effective amount of the at least one electron transfer mediator as a heterogeneous catalyst are either in a form as at least part of a groundwater permeable reactive barrier (PRB) configured as a continuous filled in trench or wall, or as a stand-alone filled in well, or, in a form as part of a groundwater pumping and treatment system. An exemplary applicable ex-situ unit for containing the catalytically effective amount of the at least one electron transfer mediator as a homogeneous catalyst or/and as a heterogeneous catalyst is in a form as part of an above surface water treatment reactor system.

Following heterogeneous catalytic treatment of the contaminated water, an electron transfer mediator solid supported or matrixed configuration type heterogeneous catalyst can be removed from a given in-situ or ex-situ unit used for treating the contaminated water, and be recycled for again treating the contaminated water. Such recycling can include, for example, subjecting the electron transfer mediator solid supported or matrixed configuration type heterogeneous catalyst to a cleaning procedure, involving selective removal of the adsorbed contaminants from the solid support or matrix, while non-destructively handling and processing the solid support or matrix.

The present invention is particularly applicable for catalytically treating water contaminated with halogenated organic compounds, wherein the halogenated organic compounds are selected from the group consisting of chlorotriazine herbicides, chloroacetanilide herbicides, halogenated aliphatic herbicides, halogen containing analogs thereof, halogen containing derivatives thereof, and combinations thereof. Nevertheless, the method and system of the present invention are generally applicable for catalytically treating water contaminated with other types or kinds of halogenated organic compounds, not limited to being halogenated organic herbicides, halogen containing analogs thereof, or halogen containing derivatives thereof.

It is to be understood that the present invention is not limited in its application to the details of the order or sequence, and number, of procedures, steps, and sub-steps, of operation or implementation of the method, or to the details of type, composition, construction, arrangement, order, and number, of the system units, system sub-units, devices, assemblies, sub-assemblies, mechanisms, structures, components, and elements, and, peripheral equipment, utilities, accessories, chemical reagents, and materials, of the system, set forth in the following illustrative description, accompanying drawings, and examples, unless otherwise specifically stated herein. The present invention is capable of other embodiments and of being practiced or carried out in various ways. Although procedures, steps, sub-steps, and system units, system sub-units, devices, assemblies, sub-assemblies, mechanisms, structures, components, and elements, and, peripheral equipment, utilities, accessories, chemical reagents, and materials, similar or equivalent to those illustratively described herein can be used for practicing or testing the present invention, suitable procedures, steps, sub-steps, and system units, system sub-units, devices, assemblies, sub-assemblies, mechanisms, structures, components, and elements, and, peripheral equipment, utilities, accessories, chemical reagents, and materials, are illustratively described herein.

It is also to be understood that all technical and scientific words, terms, or/and phrases, used herein throughout the present disclosure have either the identical or similar meaning as commonly understood by one of ordinary skill in the art to which this invention belongs, unless otherwise specifically defined or stated herein. Phraseology, terminology, and, notation, employed herein throughout the present disclosure are for the purpose of description and should not be regarded as limiting. For example, herein, the terms ‘contaminated’ and ‘polluted’ are synonymous and equivalent to each other, and the terms ‘contaminants’ and ‘pollutants’ are synonymous and equivalent to each other. Moreover, all technical and scientific words, terms, or/and phrases, introduced, defined, described, or/and exemplified, in the above Background section, are equally or similarly applicable in the illustrative description of the preferred embodiments, examples, and appended claims, of the present invention. As used herein, the term ‘about’ refers to ±10% of the associated value. Additionally, as used herein, the phrase ‘room temperature’ refers to a temperature in a range of between about 20° C. and about 25° C.

Procedures, steps, sub-steps, and, equipment and materials, system units, system sub-units, devices, assemblies, sub-assemblies, mechanisms, structures, components, and elements, and, peripheral equipment, utilities, accessories, chemical reagents, and materials, as well as operation and implementation, of exemplary preferred embodiments, alternative preferred embodiments, specific configurations, and, additional and optional aspects, characteristics, or features, thereof, of the method of catalytically treating water contaminated with halogenated organic compounds, and a system thereof, according to the present invention, are better understood with reference to the following illustrative description and accompanying drawings. Throughout the following illustrative description and accompanying drawings, same reference numbers refer to same system units, system sub-units, devices, assemblies, sub-assemblies, mechanisms, structures, components, and elements, and, peripheral equipment, utilities, chemical reagents, accessories, and materials.

In the following illustrative description of the present invention, included are main or principal procedures, steps, and sub-steps, and, main or principal system units, system sub-units, devices, assemblies, sub-assemblies, mechanisms, structures, components, and elements, and, peripheral equipment, utilities, accessories, chemical reagents, and materials, needed for sufficiently understanding proper ‘enabling’ utilization and implementation of the disclosed invention. Accordingly, description of various possible preliminary, intermediate, minor, or/and optional, procedures, steps, or/and sub-steps, or/and, system units, system sub-units, devices, assemblies, sub-assemblies, mechanisms, structures, components, and elements, and, peripheral equipment, utilities, accessories, chemical reagents, and materials, of secondary importance with respect to enabling implementation of the invention, which are readily known by one of ordinary skill in the art, or/and which are available in the prior art and technical literature relating to present invention, are at most only briefly indicated herein.

Thus, according to the first main aspect of the present invention, there is provision of a method of catalytically treating water contaminated with halogenated organic compounds, wherein the halogenated organic compounds are selected from the group consisting of chlorotriazine herbicides, chloroacetanilide herbicides, halogenated aliphatic herbicides, halogen containing analogs thereof, halogen containing derivatives thereof, and combinations thereof, the method including the procedure of exposing the contaminated water to a catalytically effective amount of at least one electron transfer mediator under reducing conditions, to thereby decrease the concentration of at least one of the halogenated organic compounds in the contaminated water.

According to the second main aspect of the present invention, there is provision of a system for catalytically treating water contaminated with halogenated organic compounds, wherein the halogenated organic compounds are selected from the group consisting of chlorotriazine herbicides, chloroacetanilide herbicides, halogenated aliphatic herbicides, halogen containing analogs thereof, halogen containing derivatives thereof, and combinations thereof, the system including: (a) at least one electron transfer mediator; and (b) at least one (in-situ or/and ex-situ) unit for containing a catalytically effective amount of the at least one electron transfer mediator, for exposing the contaminated water to the at least one electron transfer mediator under reducing conditions.

As used herein, the term ‘analogs’ of a subject (parent) compound refers to compounds each of whose molecular structure is structurally related or analogous to the subject (parent) compound molecular structure, and therefore, such compounds are expected to exhibit similar (physical, or/and chemical, or/and biological) activity(ies) as that exhibited by the subject (parent) compound.

As used herein, the term ‘derivatives’ of a subject (parent) compound refers to compounds each of whose molecular structure is derived as a result of ‘chemical modification’ of the molecular structure of the subject (parent) compound, such that a major portion of the subject (parent) compound molecular structure remains unchanged or intact in the molecular structure of each derivative compound. The chemical modification of the molecular structure of the subject (parent) compound takes place in an active manner, e.g., using synthetic organic chemistry methods and techniques, for forming an active type of derivative of the subject (parent) compound. Alternatively, or additionally, the chemical modification of the molecular structure of the subject (parent) compound takes place in a passive manner, i.e., using naturally occurring methods and techniques, for forming a passive type of derivative of the subject (parent) compound. For example, compounds each of whose molecular structure is derived by (active or/and passive) addition of at least one substituent to, or/and by a change of at least one substituent from, the molecular structure of a subject (parent) compound. For example, compounds each of whose molecular structure is derived by (active or/and passive) oxidation or hydrolysis of molecules of a subject (parent) compound.

The preceding definitions of analogs and derivatives are applicable to the halogenated organic herbicide members in the herein illustratively described chlorotriazine herbicide group (FIG. 1), the chloroacetanilide herbicide group (FIG. 2), and the halogenated aliphatic herbicide group (FIG. 3). In particular, regarding halogen containing analogs and derivatives of these halogenated organic herbicide compounds.

As used herein, consistent with that taught about and used in the art of contaminated water treatment (remediation, purification), an in-situ unit refers to a unit which is essentially physically (spatially) situated or located, and operative, at or within the actual site, place, or location, of the contaminated water, during the catalytic treatment (remediation, purification) process. Accordingly, an in-situ unit is in hydrodynamic communication with the contaminated water by means associated with, and corresponding to, the coinciding (generally same) physical (spatial) locations of the in-situ unit and the contaminated water.

As used herein, an ex-situ unit refers to a unit which is essentially physically (spatially) situated or located, and operative, out of or away from the actual site, place, or location, of the contaminated water, during the catalytic treatment (remediation, purification) process. Accordingly, an ex-situ unit is in hydrodynamic communication with the contaminated water by means associated with, and corresponding to, the non-coinciding (generally separate) physical (spatial) locations of the ex-situ unit and the contaminated water.

As illustratively described hereinbelow, with reference to FIGS. 4-7, for implementing the method and system of the present invention, exemplary applicable in-situ units for containing the catalytically effective amount of the at least one electron transfer mediator as a heterogeneous catalyst are in a form as at least part of a groundwater permeable reactive barrier (PRB) configured as a continuous filled in trench or wall (for example, in-situ unit 20 (FIG. 4)), or as a stand-alone filled in well (for example, in-situ units 30 (FIG. 5)), or in a form as part of a groundwater pumping and treatment system (for example, in-situ unit 32 (FIG. 6)). An exemplary applicable ex-situ unit for containing the catalytically effective amount of the at least one electron transfer mediator as a homogeneous catalyst or/and as a heterogeneous catalyst is in a form as part of an above surface water treatment reactor system (for example, ex-situ unit 48 (FIG. 7)).

The method of catalytically treating water contaminated with halogenated organic compounds, of the present invention, is preferably implemented by using the system for catalytically treating water contaminated with halogenated organic compounds, of the present invention. Correspondingly, the system for catalytically treating water contaminated with halogenated organic compounds, of the present invention, is preferably used for implementing the method of catalytically treating water contaminated with halogenated organic compounds, of the present invention. It is to be fully understood that the hereinbelow illustrative description is applicable to the method or/and system of the present invention, singly or in combination.

Applicable Forms of Contaminated Water:

The water contaminated with the above indicated halogenated organic compounds, herein, equivalently referred to as ‘contaminated water’, is any of a variety of different forms, such as groundwater (e.g., sub-surface water regions, reservoirs, or aquifers), surface water (e.g., rivers, lakes, ponds, pools, or surface water reservoirs), above surface water (e.g., above surface water reservoirs, or above surface sources or supplies of residential or commercial drinking water), or a combination thereof. Many such forms of contaminated water either are, or lead to, sources of water, for example, that may include drinking water, to which humans or/and animals are directly or indirectly exposed.

Applicable Halogenated Organic Compounds:

Among the halogenated organic compounds which are within the scope of application of the present invention, the chlorotriazine herbicide group, the chloroacetanilide herbicide group, and the halogenated aliphatic herbicide group, are three particularly well known halogenated organic herbicide groups, where each halogenated organic herbicide group is identified by the general characteristic or distinguishing feature or property of chemical structure which is common to each halogenated organic herbicide member in that halogenated organic herbicide group. FIGS. 1, 2, and 3, are tables listing the compound common name, chemical formula, and CAS number, and showing the chemical structure, of known halogenated organic herbicide members in each of these three respective halogenated organic herbicide groups. Each of these known halogenated organic herbicide members also has other, less commonly used, chemical names, for example, as assigned by CAS and IUPAC, which, although not listed herein, appear in published chemical literature and related prior art.

The chlorotriazine herbicide group, as identified and illustrated in FIG. 1, refers to and includes halogenated organic herbicides having the general chemical structure shown hereinbelow, wherein R₁-R₄ are each independently selected from the group consisting of a hydrogen atom [H] and an organic substituent:

Thus, each of R₁ to R₄ is independently, for example, hydrogen, or an organic substituent, such as, but not limited to, alkyl (e.g., methyl, ethyl, isopropyl), cycloalkyl (e.g., cyclopropyl), cyanoalkyl, alkenyl, alkynyl, carboxylic acid (e.g., acetic acid), ether, alkoxy, heteroaryl, aryl, heteroalicyclic, and the like.

With reference to FIG. 1, the chlorotriazine herbicide group includes the following known halogenated organic herbicides: atrazine [C₈H₁₄ClN₅], chlorazine [C₁₁H₂₀ClN₅], cyanazine [C₉H₁₃ClN₆], cyprazine [C₉H₁₄ClN₅], eglinazine [C₇H₁₀ClN₅O₂], ipazine [C₁₀H₁₈ClN₅], mesoprazine [C₁₀H₁₈ClN₅O], procyazine [C₁₀H₁₃ClN₆], proglinazine [C₈H₁₂ClN₅O₂], propazine [C₉H₁₆ClN₅], sebuthylazine [C₉H₁₆ClN₅], simazine [C₇H₁₂ClN₅], terbuthylazine [C₉H₁₆ClN₅], and, trietazine

[C₉H₁₆ClN₅].

Additional halogenated organic compounds also within the scope of application of the present invention are halogen containing analogs, and halogen containing derivatives, of halogenated organic herbicide members in the above illustratively described chlorotriazine herbicide group, in which each of R₁ to R₄ in the above general chemical structure of the chlorotriazine herbicide group is as described herein.

The chloroacetanilide herbicide group, as identified and illustrated in FIG. 2, refers to and includes halogenated organic herbicides having the general chemical structure shown hereinbelow, wherein R₁-R₄ are each independently selected from the group consisting of a hydrogen atom [H] and an organic substituent as described hereinabove:

With reference to FIG. 2, the chloroacetanilide herbicide group includes the following known halogenated organic herbicides: acetochlor [C₁₄H₂₀ClNO₂], alachlor [C₁₄H₂₀ClNO₂], butachlor [C₁₇H₂₆ClNO₂], metazachlor [C₁₄H₁₆ClN₃O], metolachlor [C₁₅H₂₂ClNO₂], S-metolachlor [C₁₅H₂₂ClNO₂], pretilachlor [C₁₇H₂₆ClNO₂], propachlor [C₁₁H₁₄ClNO], xylachlor [C₁₃H₁₈ClNO], butenachlor [C₁₇H₂₄ClNO₂], delachlor [C₁₅H₂₂ClNO₂], diethatyl [C₁₄H₁₈ClNO₃], dimethachlor [C₁₃H₁₈ClNO₂], propisochlor [C₁₅H₂₂ClNO₂], prynachlor [C₁₂H₁₂ClNO], terbuchlor [C₁₈H₂₈ClNO₂], and thenylchlor [C₁₆H₁₈ClNO₂S].

Additional halogenated organic compounds also within the scope of application of the present invention are halogen containing analogs, and halogen containing derivatives, of halogenated organic herbicide members in the above illustratively described chloroacetanilide herbicide group, in which each of R₁ to R₄ in the above general chemical structure of the chloroacetanilide herbicide group is as described herein.

Halogenated organic herbicide members in the chlorotriazine herbicide group (FIG. 1), particularly triazines, such as atrazine and cyanazine, and in the chloroacetanilide herbicide group (FIG. 2), particularly alachlor and metolachlor, are the most widely used agricultural chemicals (agrochemicals). Such halogenated organic herbicides are commonly referred to as chlorinated organonitrogen herbicides (CONHs), indicating presence of nitrogen in addition to the chlorine halogen.

The halogenated aliphatic herbicide group, as identified and illustrated in FIG. 3, refers to and includes halogenated organic herbicides having the general chemical structure shown hereinbelow, wherein n ranges from 1 to 4, and, A, B, R′, and R″, are each independently selected from the group consisting of a hydrogen atom [H] and an organic substituent, whereas at least one of A, B, R′, and R″ is a halogen atom (i.e., fluorine [F], chlorine [Cl], bromine [Br], or iodine [I]):

A-(C—R′—R″)_(n)—B

Accordingly, halogenated organic herbicide members in the halogenated aliphatic herbicide group (FIG. 3) have the general chemical structure of an organic compound in which the carbon atoms are linked in an open chain with at least one carbon atom bonded to a halogen atom. Thus, for example, n ranges from 1 to 4, usually from 1 to 2; A is a halogen atom, a hydrogen atom, or an alkyl; each of R′ and R″ is independently a halogen atom, a hydrogen atom, or an alkyl; and B is a hydrogen atom, a halogen atom, an alkyl, or —(C═O)W, wherein W is hydroxy, a haloalkyl (e.g., trihaloalkyl), or, for example, —C—(R′)═C—(R″)—C(═O)—OOH, wherein R′ and R″ are as described hereinabove.

With reference to FIG. 3, the halogenated aliphatic herbicide group includes the following known halogenated organic herbicides: alorac [C₅HCl₅O₃], chloropon [C₃H₃Cl₃O₂], dalapon [C₃H₄Cl₂O₂], flupropanate [C₃H₂F₄O₂], TCA (trichloroacetic acid) [C₂HCl₃O₂], hexachloroacetone [C₃Cl₆O], iodomethane [CH₃₁], methyl bromide [CH₃Br], monochloroacetic acid [C₂H₃ClO₂], and SMA (sodium chloroacetate) [C₂H₂ClNaO₂].

Additional halogenated organic compounds also within the scope of application of the present invention are halogen containing analogs, and halogen containing derivatives, of halogenated organic herbicide members in the above illustratively described halogenated aliphatic herbicide group, in which each of A, B, R′, and R″, and n, in the above general chemical structure of the halogenated aliphatic herbicide group is as described herein.

As used herein, the term ‘alkyl’ describes a saturated aliphatic hydrocarbon including straight chain and branched chain groups. Preferably, the alkyl group has 1 to 20 carbon atoms. Whenever a numerical range, for example, ‘1 to 20’, is stated herein, it implies that the group, in this case the alkyl group, contains 1 carbon atom, 2 carbon atoms, 3 carbon atoms, etc., up to and including 20 carbon atoms. More preferably, the alkyl is a medium size alkyl having 1 to 10 carbon atoms. Most preferably, unless otherwise indicated, the alkyl is a lower alkyl having 1 to 4 carbon atoms. The alkyl group is substituted or unsubstituted. When substituted, the substituent group is, for example, trihaloalkyl, cycloalkyl, alkenyl, alkynyl, aryl, heteroaryl, heteroalicyclic, halo, hydroxy, alkoxy, aryloxy, thiohydroxy, thioalkoxy, thioaryloxy, sulfinyl, sulfonyl, cyano, nitro, azo, sulfonyl, sulfinyl, carbonyl, thiocarbonyl, ester, ether, carboxy, thiocarboxy, thioether, and amino.

The term ‘cycloalkyl’ describes an all carbon monocyclic or fused ring (i.e., rings which share an adjacent pair of carbon atoms) group wherein one of more of the rings does not have a completely conjugated pi-electron system. Examples, without limitation, of cycloalkyl groups are cyclopropane, cyclobutane, cyclopentane, cyclopentene, cyclohexane, cyclohexadiene, cycloheptane, cycloheptatriene, and adamantane. The cycloalkyl group is substituted or unsubstituted.

An ‘alkenyl’ group refers to an alkyl group which consists of at least two carbon atoms and at least one carbon-carbon double bond.

An ‘alkynyl’ group refers to an alkyl group which consists of at least two carbon atoms and at least one carbon-carbon triple bond.

An ‘aryl’ group refers to an all-carbon monocyclic or fused-ring polycyclic (i.e., rings which share adjacent pairs of carbon atoms) groups having a completely conjugated pi-electron system. Examples, without limitation, of aryl groups are phenyl, naphthalenyl and anthracenyl. The aryl group is substituted or unsubstituted.

A ‘heteroaryl’ group refers to a monocyclic or fused ring (i.e., rings which share an adjacent pair of atoms) group having in the ring(s) one or more atoms, such as, for example, nitrogen, oxygen and sulfur and, in addition, having a completely conjugated pi-electron system. Examples, without limitation, of heteroaryl groups include pyrrole, furane, thiophene, imidazole, oxazole, thiazole, pyrazole, pyridine, pyrimidine, quinoline, isoquinoline and purine. The heteroaryl group is substituted or unsubstituted. When substituted, the substituent group is, for example, alkyl, hydroxyalkyl, trihaloalkyl, cycloalkyl, alkenyl, alkynyl, aryl, heteroaryl, heteroalicyclic, halo, hydroxy, alkoxy, aryloxy, thiohydroxy, thioalkoxy, thioaryloxy, sulfinyl, sulfonyl, cyano, nitro, azo, sulfonyl, sulfinyl, and amino.

A ‘heteroalicyclic’ group refers to a monocyclic or fused ring group having in the ring(s) one or more atoms such as nitrogen, oxygen and sulfur. The rings may also have one or more double bonds. However, the rings do not have a completely conjugated pi-electron system. The heteroalicyclic is substituted or unsubstituted.

A ‘hydroxy’ group refers to an —H group.

An ‘azo’ group refers to a —N═N group.

An ‘alkoxy’ group refers to both an —O-alkyl and an —O-cycloalkyl group, as defined herein.

An ‘aryloxy’ group refers to both an —O-aryl and an —O-heteroaryl group, as defined herein.

A ‘thiohydroxy’ group refers to an —SH group.

A ‘thioalkoxy’ group refers to both an —S-alkyl group, and an —S-cycloalkyl group, as defined herein.

A ‘thioaryloxy’ group refers to both an —S-aryl and an —S-heteroaryl group, as defined herein.

A ‘carbonyl’ group refers to a —C(═O)—R group, wherein R is hydrogen, alkyl, alkenyl, cycloalkyl, aryl, heteroaryl (bonded through a ring carbon) or heteroalicyclic (bonded through a ring carbon), as defined herein.

A ‘carboxylic acid’ group refers to an —R—C(═O)|OH group, wherein R is alkyl, cycloalkyl, or aryl, as defined herein.

A ‘halo’ group, which is also referred to herein as ‘halogen’ refers to fluorine, chlorine, bromine or iodine.

A ‘trihalomethyl’ group refers to a —CX group, wherein X is a halo group as defined herein.

An ‘amino’ group refers to an —NR′R″ group, wherein R′ and R″ are as defined herein.

A ‘nitro’ group refers to an —NO₂ group.

A ‘cyano’ group refers to a —C≡N group.

An ‘ether’ group refers to a —R—O—R′ group, wherein each of R and R′ is independently an alkyl as defined herein.

As stated, the scope of application of the present invention is particularly directed to the above illustratively described three halogenated organic herbicide groups and the halogenated organic herbicide members therein, halogen containing analogs thereof, and halogen containing derivatives thereof, and combinations thereof, as being specific types or categories of the broader and more general category of halogenated organic compounds. The indicated halogenated organic herbicide compounds, at room temperature (between about 20° C. and about 25° C.) and atmospheric pressure, are non-volatile particulate substances (nearly all) or liquids (some) which, at typical contaminant concentrations (e.g., ppb-ppm range) are mobile and soluble in water, and are of particular interest in the field of environmental science and technology focusing on treating or remediating contaminated or polluted water.

The method and system of the present invention are based on using a chemical technique for catalytically treating the contaminated water, by exploiting catalytic chemical reaction types of phenomena, mechanisms, and processes, involving the use of at least one electron transfer mediator functioning as an active redox catalyst under reducing (anaerobic or anoxic) conditions, for in-situ or ex-situ, homogeneously or heterogeneously, catalytically degrading, transforming, or converting, in particular, via reductive dehalogenation (typically, dechlorination) of, the halogenated organic compounds in the contaminated water to non-hazardous or/and less hazardous (poisonous or toxic) chemical species. Implementation of the present invention results in decreasing the concentration of at least one of the halogenated organic compounds in the contaminated water.

Electron Transfer Mediators:

As used herein, an ‘electron transfer mediator’ is a chemical substance, functioning as a catalyst or co-catalyst, which is catalytically active, and expedites (catalyzes) redox (reduction-oxidation) types of chemical reactions, such as reductive dehalogenation, by participating in, mediating, and expediting, the transfer of electrons from a bulk electron donor or reducing agent to an electron acceptor, or/and by stabilizing intermediate forms of the redox reactants. An electron transfer mediator which specifically functions by participating in, mediating, and expediting, the transfer of electrons from an electron donor or reducing agent to an electron acceptor is also known as an electron carrier or as an electron shuttle, since electrons are carried and shuttled by such a chemical species. Description, general mechanisms (with reference to chemical equations (1) and (2)), and prior art teachings, of reductive dehalogenation, in general, and of zero valent metal (ZVM) reductive dehalogenation, in particular, of halogenated organic compounds (other than those within the scope of application of the present invention), catalyzed by an electron transfer mediator catalyst, are provided hereinabove in the Background section.

In general, essentially any electron transfer mediator functioning as an active redox catalyst under reducing (anaerobic or anoxic) conditions can be used for implementing the method and system of the present invention. Preferably, the at least one electron transfer mediator is selected from the group consisting of a porphyrinogenic organometallic complex, an analog thereof, a derivative thereof, and any combination thereof. The hereinabove provided definitions of analogs and derivatives of a subject compound are applicable to analogs and derivatives, respectively, of a porphyrinogenic organometallic complex subject (parent) compound.

As used herein, a ‘porphyrinogenic organometallic complex’ means an organometallic complex formed between a neutral metal atom or a metal ion and a porphyrinogenic or porphyrinogenic-like ring system. As used herein, a ‘porphyrinogenic or ‘porphyrinogenic-like ring system’ means a system in which 5-membered heterocyclic rings are linked in a macrocyclic ring structure by linking groups. The linking groups are saturated or/and unsaturated and have saturated or/and unsaturated side chains such that a complete or partial pi-conjugation is formed between the macrocyclic rings and the unsaturated linking groups or/and side chains in the system. The porphyrinogenic or ‘porphyrinogenic-like ring system preferably also has sufficient non-conjugated electrons to form covalent or coordinate bonds with the metal.

It is to be fully understood that the term ‘porphyrinogenic organometallic complex’ as used herein encompasses an organometallic complex formed between a neutral metal atom or a metal ion, and an analog or derivative of the just defined porphyrinogenic or porphyrinogenic-like ring system.

There are extensive teachings [e.g., 79] about the origin, and the numerous physical, chemical, and biological, properties, characteristics, and behavior, of porphyrinogenic organometallic complexes, of which thousands have been identified and studied [e.g., 80, 81]. Porphyrinogenic organometallic complexes exhibit several particular properties, characteristics, and behavior, which make them especially well applicable for functioning as electron transfer mediator type catalysts in homogeneous or heterogeneous electron transfer mediated catalytic reductive dehalogenation (typically, dechlorination) reaction systems, for catalyzing reductive dehalogenation of halogenated organic compound contaminants, such as halogenated organic herbicides, in general, for example, herbicide members in the above illustratively described three herbicide groups (FIGS. 1, 2, and 3), and chlorinated organonitrogen herbicides (CONHs), in particular, in water under reducing (anaerobic or anoxic) conditions.

Porphyrinogenic organometallic complexes are: (1) effective redox catalysts for many reactions, and have a long range of redox activity; (2) electrochemically active with almost any core metal; (3) active catalysts in aqueous solution under conditions pertinent to environments of various different forms of contaminated water, such as groundwater, surface water, and above surface water; and (4) relatively highly stable, thereby enabling reactions to take place under severe conditions, where other types of reactions probably would not take place.

For implementing the method and system of the present invention, preferably, the at least one porphyrinogenic organometallic complex is selected from the group consisting of a metalloporphyrin complex, a metallocorrin complex, a metallochlorin complex, and any combination thereof. Preferably, the at least one porphyrinogenic organometallic complex includes at least one metalloporphyrin complex. Metalloporphyrin complexes (commonly known and referred to as metalloporphyrins), being porphyrinogenic organometallic complexes of metal ions and porphyrin ligands, are organic tetrapyrrole macrocycles composed of four pyrrole type rings joined by methane (methylidene) bridges and complexed to a central metal ion. They form a near planar structure of aromatic macrocycles containing up to 22 conjugated π electrons, 18 of which are incorporated into the delocalization pathway in accordance with Huckel's [4n+2] rule of aromaticity. One or two of the peripheral double bonds of the porphyrin ligands of a metalloporphyrin can undergo an addition reaction to form a metalloporphyrin derivative, such as a metallocorrin or a metallochlorin type of porphyrinogenic organometallic complex.

Preferably, the metalloporphyrin complex is composed of a transition metal complexed to a (initially free base) porphyrin selected from the group consisting of:

-   tetramethylpyridilporphyrin, also named and known as     [5,10,15,20-tetrakis(1-methyl-4-pyridinio)-porphine], herein,     abbreviated and also referred to as [TMPyP]; -   tetrahydroxyphenylporphyrine, also named and known as     [5,10,15,20-tetrakis(4-hydroxyphenyl)-21H,23H-porphine], herein,     abbreviated and also referred to as [TP(OH)P]; -   tetraphenylporphyrin, also named and known as     [5,10,15,20-tetraphenyl-21H,23H-porphine], herein, abbreviated and     also referred to as [TPP]; and -   4,4′,4″,4″′-(porphine-5,10,15,20-tetrayl)tetrakis(benzenesulfonic     acid), herein, abbreviated and also referred to as [TBSP].

The transition metal is essentially any transition metal capable of complexing with the just stated porphyrins for forming the corresponding metalloporphyrin complex. Preferably, the transition metal is selected from the group consisting of cobalt [Co], nickel [Ni], iron [Fe], zinc [Zn], and copper [Cu].

Accordingly, for implementing the present invention, preferred metalloporphyrin complexes are:

tetramethylpyridilporphyrin-transition metal, also named and known as [5,10,15,20-tetrakis(1-methyl-4-pyridinio)-porphine-transition metal], herein, abbreviated and also referred to as [TMPyP-transition metal];

tetrahydroxyphenylporphyrine-transition metal, also named and known as [5,10,15,20-tetrakis(4-hydroxyphenyl)-21H,23H-porphine-transition metal], herein, abbreviated and also referred to as [TP(OH)P-transition metal];

tetraphenylporphyrin-transition metal, also named and known as [5,10,15,20-tetraphenyl-21H,23H-porphine-transition metal] [TPP-transition metal]; and

4,4′,4″,4″′-(porphine-5,10,15,20-tetrayl)tetrakis(benzenesulfonic acid)transition metal, herein, abbreviated and also referred to as [TBSP-transition metal],

where, in each metalloporphyrin complex the transition metal is cobalt [Co], nickel [Ni], iron [Fe], zinc [Zn], or copper [Cu].

The above indicated [TMPyP-transition metal], [TP(OH)P-transition metal], [TPP-transition metal], and [TBSP-transition metal], preferred metalloporphyrin complexes are either commercially available, or are synthesized from the commercially available respective [TMPyP], [TP(OH)P], [TPP], and [TBSP], (free base) porphyrins and transition metal solutions using published methods and techniques [e.g., 100, 101, 61].

Additional exemplary metalloporphyrin complexes which are suitable for implementing the present invention are selected from the group consisting of chlorophylls [magnesium (II) complexes], and hemes [iron (II) complexes]. An exemplary metallocorrin complex which is suitable for implementing the present invention is vitamin B₁₂ [corrin ligand (porphyrin analog) complexed to a cobalt (III) ion]. These additional exemplary metalloporphyrin complexes are commercially available.

As used herein, a ‘catalytically effective amount of at least one electron transfer mediator’ means the amount (expressed, for example, in terms of a molar concentration, or alternatively, in terms of a mass (weight) ratio) of the at least one electron transfer mediator (functioning as either a homogeneous catalyst, or as the main catalytic component of a heterogeneous catalyst) to which the contaminated water is exposed, such that the at least one electron transfer mediator in the contaminated water under reducing (anaerobic or anoxic) conditions effectively catalytically decreases the concentration of at least one of the halogenated organic compound contaminants in the contaminated water.

Catalytically treating the contaminated water, by exposing the contaminated water to the catalytically effective amount of at least one electron transfer mediator under reducing conditions, involving catalytic degradation, transformation, or conversion, of the halogenated organic compounds in the contaminated water to non-hazardous or/and less hazardous chemical species, thereby decreasing the concentration of at least one of the halogenated organic compounds in the contaminated water, is effected according to homogeneous catalysis, according to heterogeneous catalysis, or according to a combination thereof.

According to homogeneous catalysis, the at least one electron transfer mediator (catalyst) is an initially solid (typically, particulate) substance that is non-supported, non-matrixed, non-intercalated, or/and non-trapped, by another material, and subsequently becomes freely mobile and soluble throughout the contaminated water.

According to heterogeneous catalysis, the at least one electron transfer mediator (catalyst) is an initially solid (typically, particulate) substance that is supported, matrixed, intercalated, incorporated, or/and trapped, and generally immobile, on or/and inside of a (particulate or/and non-particulate) solid support or matrix material which subsequently becomes dispersed (i.e., not dissolved) throughout the contaminated water. Ordinarily, the initially immobilized at least one electron transfer mediator (catalyst) similarly becomes dispersed (i.e., not dissolved) throughout the contaminated water. However, any one or more immobilized electron transfer mediator may at least partially dissolve in the contaminated water, depending upon actual parameters and conditions of a given heterogeneous catalytic chemical reaction system during implementation of the present invention.

For implementing the method and system of the present invention according to heterogeneous catalysis, in general, essentially any type of heterogeneous catalyst (preferably, but not limited to being, particulate) solid support or matrix material can be used for supporting, matrixing, and immobilizing, the at least one electron transfer mediator (catalyst). Exemplary types of suitable (particulate or/and non-particulate) solid support or matrix materials are diatomite (kieselguhr), amorphous silicas, crystalline silicas, silica gels, aluminas, minerals, ceramics, carbohydrates (such as sepharose, sephadex), clays, plastics (such as polystyrene), composites, and combinations thereof.

A specific example of such an electron transfer mediator solid supported or matrixed configuration is a diatomite/zero valent metal (ZVM)/electron transfer mediator composite type of heterogeneous catalyst, composed of a powdered diatomite (kieselguhr) support or matrix (optionally, including vermiculite) on or/and into which are incorporated at least one (preferably, porphyrinogenic organometallic complex type of) electron transfer mediator functioning as a catalyst, and zero valent metal (ZVM) nanometer sized particles, for example, having a size in a range of between about 5 nm and about 600 nm, functioning as a bulk electron donor or reducing agent, as described by the present assignee/applicant in PCT Int'l. Pat. Appl. Pub. No. WO 2006/072944, published Jul. 13, 2006, entitled: “Zero Valent Metal Composite Catalyst, Manufacturing, System And Method Using Thereof, For Catalytically Treating Contaminated Water”.

It is noted that following heterogeneous catalytic treatment of the contaminated water, an electron transfer mediator solid supported or matrixed configuration type heterogeneous catalyst can be removed from a given in-situ or ex-situ unit used for treating the contaminated water, and be recycled for again treating the contaminated water. Such recycling can include, for example, subjecting the electron transfer mediator solid supported or matrixed configuration type heterogeneous catalyst to a cleaning procedure, involving selective removal of the adsorbed contaminants from the solid support or matrix, while non-destructively handling and processing the solid support or matrix.

Thus, for implementing the method and system of the present invention according to homogeneous catalysis, the above defined catalytically effective amount of the at least one electron transfer mediator to which the contaminated water is exposed, refers specifically to the amount of the at least one electron transfer mediator (catalyst) which is an initially solid (typically, particulate) substance that is non-supported, non-matrixed, non-intercalated, non-intercalated, or/and non-trapped, by another material, and subsequently becomes freely mobile and soluble throughout the contaminated water.

Thus, for implementing the method and system of the present invention alternatively, or additionally, according to heterogeneous catalysis, the above defined catalytically effective amount of the at least one electron transfer mediator to which the contaminated water is exposed, refers specifically to the amount of the at least one electron transfer mediator (catalyst) which is an initially solid (typically, particulate) substance that is supported, matrixed, intercalated, incorporated, or/and trapped, and generally immobile, on or/and inside of a (particulate or/and non-particulate) solid support or matrix material which subsequently becomes dispersed throughout the contaminated water.

In general, the catalytically effective amount of the at least one electron transfer mediator to which the contaminated water is exposed can be varied. The catalytically effective amount of the at least one electron transfer mediator to which the contaminated water is exposed, expressed in terms of a molar concentration, corresponds to the number of moles of the at least one electron transfer mediator per unit volume (for example, liter) of the contaminated water, and is written as moles electron transfer mediator per liter contaminated water. The catalytically effective amount of the at least one electron transfer mediator to which the contaminated water is exposed, in terms of a molar concentration, is in a range of, preferably, between about 10⁻⁷ and about 10⁻³ mole electron transfer mediator per liter contaminated water, and more preferably, between about 10⁻⁶ and about 10⁻⁴ mole electron transfer mediator per liter contaminated water. The optimum catalytically effective amount of the at least one electron transfer mediator to which the contaminated water is exposed, in terms of a molar concentration, is about 10⁻⁵ mole electron transfer mediator per liter contaminated water.

Alternatively, the catalytically effective amount of the at least one electron transfer mediator to which the contaminated water is exposed, expressed in terms of a mass (weight) ratio, corresponds to the ratio of the mass (weight) (for example, ‘x’ mass (weight) units) of the at least one electron transfer mediator and the mass (weight) (for example, ‘y’ mass (weight) units) of at least one of the halogenated organic compound contaminants in the contaminated water. This mass (weight) ratio is written as a ratio of two numbers, for example, x:y, without units or dimensions, with clear understanding that the units or dimensions of mass (weight) are the same for each of the mass (weight) of the electron transfer mediator and the mass (weight) of at least one of the halogenated organic compound contaminants in the contaminated water. The catalytically effective amount of the at least one electron transfer mediator to which the contaminated water is exposed, in terms of a mass (weight) ratio of the at least one electron transfer mediator and at least one of the halogenated organic compound contaminants in the contaminated water, is in a range of, preferably, between about 1:1000 and about 1000:1; more preferably, between about 1:100 and about 100:1; and most preferably, between about 1:10 and about 10:1.

As stated hereinabove, in general, essentially any electron transfer mediator functioning as an active redox catalyst under reducing (anaerobic or anoxic) conditions can be used for implementing the method of the present invention, and in general, the catalytically effective amount of the at least one electron transfer mediator to which the contaminated water is exposed can be varied. The actual type, and catalytically effective amount, of the at least one electron transfer mediator to which the contaminated water is exposed, depends upon several parameters, which can be categorized as primary, secondary, and tertiary, parameters.

Exemplary primary parameters are the types, quantities, concentrations, and, physicochemical properties, characteristics, and behavior, such as chemical structure, chemical reactivity, solubility, of the targeted (known or/and suspected) halogenated organic compound contaminants in the contaminated water. Additional primary parameters are the physicochemical properties, characteristics, and behavior, such as chemical structure, chemical (catalytic) reactivity, solubility, of the at least one electron transfer mediator. For implementing the present invention, preferably, an attempt is made at correlating or associating the physicochemical properties, characteristics, and behavior, of the at least one electron transfer mediator with those of the targeted halogenated organic compound contaminants in the contaminated water.

Exemplary secondary parameters are the bulk quantity (in terms of total volume or mass, or, alternatively, in terms of volume or mass flow rates), and, physicochemical and hydrodynamic (flow) properties, characteristics, and behavior, of the contaminated water. These secondary parameters particularly depend upon the form of the contaminated water, for example, as groundwater (e.g., sub-surface water region, reservoir, or aquifer), as surface water (e.g., river, lake, pond, pool, or surface water reservoir), as above surface water (e.g., above surface water reservoir, or above surface source or supply of residential or commercial drinking water), or as a combination thereof.

Exemplary tertiary parameters are the temperature, pH, pressure, and gradients thereof, of the contaminated water. Additional tertiary parameters are the types, quantities, concentrations, and, physicochemical properties, characteristics, and behavior, such as chemical structures, chemical reactivities, solubilities, of other known or/and possible substances or materials present throughout the immediate vicinity of the contaminated water which is to be exposed to the catalytically effective amount of the at least one electron transfer mediator.

Exposing the Contaminated Water to the Electron Transfer Electron Mediator(s):

In general, exposing the contaminated water to the catalytically effective amount of the at least one electron transfer mediator is performed according to any of a variety of different manners or ways well known in the art for forming a homogeneous or heterogeneous catalytic reaction system. Exposing the contaminated water to the catalytically effective amount of the at least one electron transfer mediator is performed, for example, according to homogeneous catalysis or/and according to heterogeneous catalysis, each via a batch mode, or, alternatively, each via a flow mode, for forming a respective homogeneous or heterogeneous catalytic reaction system of either mode.

A given homogeneous or heterogeneous catalytic reaction system, operated via a batch or flow mode, enables catalytically treating the contaminated water, by exploiting catalytic chemical reaction types of phenomena, mechanisms, and processes, involving the use of the at least one electron transfer mediator functioning as an active redox catalyst under reducing (anaerobic or anoxic) conditions, for in-situ or ex-situ, homogeneously or heterogeneously, catalytically degrading, transforming, or converting, in particular, via reductive dehalogenation (typically, dechlorination) of, the halogenated organic compounds in the contaminated water to non-hazardous or/and less hazardous (poisonous or toxic) chemical species.

Several exemplary specific preferred manners or ways of exposing the contaminated water to the catalytically effective amount of the at least one electron transfer mediator are presented hereinbelow. It is to be fully understood that implementation of the method and system of the present invention is not limited to the following exemplary specific preferred manners or ways of exposure, as other manners or ways for forming a batch mode or flow mode type of homogeneous or heterogeneous catalytic reaction system can be used for exposing the contaminated water to the catalytically effective amount of the at least one electron transfer mediator.

Homogeneous Catalysis:

For any of the hereinbelow described exemplary specific preferred manners or ways of exposing the contaminated water to the catalytically effective amount of the at least one electron transfer mediator, according to homogeneous catalysis, via a batch or flow mode, the catalytically effective amount of the at least one electron transfer mediator is an initially solid (typically, particulate) substance that is non-supported, non-matrixed, non-intercalated, or/and non-trapped, by another material. Upon exposure to the contaminated water, the catalytically effective amount of the at least one electron transfer mediator becomes freely mobile and soluble throughout the contaminated water.

Either part of, or the entire, catalytically effective amount of the at least one electron transfer mediator is used ‘as is’, in a solid (typically, particulate) form, i.e., as a generally dry, single solid (typically, particulate) substance or mixture of several solid (typically, particulate) substances. Alternatively, or additionally, prior to exposure to the contaminated water, either part of, or the entire, catalytically effective amount of the at least one electron transfer mediator is dissolved in one or more suitable (aqueous or/and organic) solvents at suitable conditions (temperature, pH, mixing), and then used in a solution form, i.e., as a solution of a dissolved single solid (typically, particulate) substance or as a solution of a dissolved mixture of several solid (typically, particulate) substances.

As discussed immediately following, a suitable solvent for dissolving a given electron transfer mediator particularly depends upon the electron transfer mediator being water soluble or water insoluble. Exemplary suitable solvents and suitable conditions for each case are provided hereinbelow.

Electron Transfer Mediator Solubility Considerations for Forming Homogeneous Catalytic Reaction Systems:

For any of the hereinbelow described exemplary specific preferred manners or ways of exposing the contaminated water to the catalytically effective amount of the at least one electron transfer mediator, according to homogeneous catalysis, via a batch or flow mode, each electron transfer mediator (being an initially solid (typically, particulate) substance that is non-supported, non-matrixed, non-intercalated, or/and non-trapped, by another material) subsequent to exposure to the contaminated water, needs to become freely mobile and soluble throughout the contaminated water, in order to form the hereinbelow described batch or flow mode homogeneous catalytic reaction systems.

In general, any number of the at least one electron transfer mediator is/are soluble or insoluble in pure or clean (uncontaminated) water (i.e., not the contaminated water being treated by the present invention), such as distilled deionized filtered water. In general, those electron transfer mediators which are soluble in pure or clean water are either expected to be, or tested as being, sufficiently soluble in the contaminated water, if exposed to the contaminated water. Likewise, those electron transfer mediators which are insoluble in pure or clean water are either expected to be, or tested as being, insoluble, or at best, insufficiently soluble, in the contaminated water, if exposed to the contaminated water.

Clearly, the extent or degree of solubility, or lack thereof, of a given electron transfer mediator in the contaminated water depends primarily upon: (a) the type, quantity, concentration, and, physicochemical properties, characteristics, and behavior, of the given electron transfer mediator; (b) the bulk quantity, and, physicochemical and hydrodynamic (flow) properties, characteristics, behavior, conditions (in particular, temperature, pH, pressure, and gradients thereof), and form, of the contaminated water, for example, as groundwater, as surface water, as above surface water, or as a combination thereof; and (c) the types, quantities, concentrations, and, physicochemical properties, characteristics, and behavior, such as chemical structures, chemical reactivities, solubilities, of other known or/and possible substances or materials present throughout the immediate vicinity of the contaminated water which is exposed to the given electron transfer mediator.

Among the wide variety of the hereinabove previously described electron transfer mediators, most, but certainly not all, are insoluble in pure or clean water, and are either expected to be, or tested as being, insoluble, or at best, insufficiently soluble, in the contaminated water, if exposed to the contaminated water. For example, it is well known [e.g., 79] that most, but not all, porphyrinogenic organometallic complexes, any of which is generally applicable as an electron transfer mediator (catalyst) for implementing the method of the present invention, are generally insoluble in pure or clean water, and are expected to be insoluble, or at best, insufficiently soluble, in the contaminated water, if exposed to the contaminated water.

Electron Transfer Mediator(s) being Water Soluble:

According to homogeneous catalysis, via a batch or flow mode, wherein any one or more electron transfer mediator, or all electron transfer mediators, of the entire catalytically effective amount of the at least one electron transfer mediator is/are soluble in pure or clean water, and is/are either expected to be, or tested as being, sufficiently soluble in the contaminated water, then, any one or more water soluble electron transfer mediator, singly or in combination, is/are used as is, in a particulate form, i.e., as a generally dry, single particulate substance or mixture of several particulate substances. Alternatively, or additionally, prior to exposure to the contaminated water, any one or more water soluble electron transfer mediator, singly or in combination, is/are dissolved in pure or clean (uncontaminated) water, such as distilled deionized filtered water, at suitable conditions (temperature, pH, mixing), and then used in a solution form, i.e., as a solution of a dissolved single particulate substance or as a solution of a dissolved mixture of several particulate substances.

For dissolving any one or more water soluble electron transfer mediator, or all water soluble electron transfer mediators, of the catalytically effective amount of the at least one electron transfer mediator, in pure or clean (uncontaminated) water, such as distilled deionized filtered water, exemplary preferred suitable conditions correspond to room temperature (temperature between about 20° C. and about 25° C.); pH in a range of, preferably, between about 1 and about 14; more preferably, between about 5 and about 9, and most preferably, between about 6 and about 8; with mixing.

Exemplary water soluble electron transfer mediators (catalysts) which are particularly applicable for implementing the method of the present invention, according to homogeneous catalysis, via a batch or flow mode, as described hereinabove and hereinbelow, are the previously described tetramethylpyridilporphyrin-transition metal [5,10,15,20-tetrakis(1-methyl-4-pyridinio)-porphine-transition metal] [TMPyP-transition metal] metalloporphyrin complexes, and the previously described tetrahydroxyphenylporphyrine-transition metal [5,10,15,20-tetrakis(4-hydroxyphenyl)-21H,23H-porphine-transition metal] [TP(OH)P-transition metal] metalloporphyrin complexes, wherein, preferably, the transition metal is selected from the group consisting of cobalt [Co], nickel [Ni], iron [Fe], zinc [Zn], and copper [Cu].

The above indicated [TMPyP-transition metal] metalloporphyrin complexes are generally soluble in pure or clean water, within the ranges of the above stated exemplary suitable conditions (room temperature; pH in a range of between about 5 and about 9; with mixing), and are either expected to be, or tested as being, sufficiently soluble in the contaminated water. The above indicated [TP(OH)P-transition metal] metalloporphyrin complexes are generally soluble in pure or clean water, within the ranges of the above stated exemplary suitable conditions (room temperature; pH greater than about 7.5; with mixing), and are either expected to be, or tested as being, sufficiently soluble in the contaminated water.

Thus, any one or more of the above indicated [TMPyP-transition metal] electron transfer mediators or/and [TP(OH)P-transition metal] electron transfer mediators, singly or in combination, is/are used as is, in a particulate form, i.e., as a generally dry, single particulate substance or mixture of several particulate substances, for being exposed to the contaminated water. Alternatively, or additionally, prior to exposure to the contaminated water, any one or more of these metalloporphyrin complex type electron transfer mediators, singly or in combination, is/are dissolved in pure or clean (uncontaminated) water, such as distilled deionized filtered water, within the ranges of the above stated suitable conditions (temperature, pH, mixing), and then used in a solution form, i.e., as a solution of a dissolved single particulate substance or as a solution of a dissolved mixture of several particulate substances, for being exposed to the contaminated water.

Electron Transfer Mediator(s) being Water Insoluble:

According to homogeneous catalysis, via a batch or flow mode, wherein any one or more electron transfer mediator, or all electron transfer mediators, of the entire catalytically effective amount of the at least one electron transfer mediator is/are insoluble in pure or clean water, and is/are either expected to be, or tested as being, insoluble, or at best, insufficiently soluble, in the contaminated water, then, prior to exposure to the contaminated water, any one or more water insoluble electron transfer mediator, singly or in combination, is/are dissolved in a suitable organic containing solvent, at suitable conditions (e.g., room temperature, with mixing), and then used in a solution form, i.e., as a solution of a dissolved single particulate substance or as a solution of a dissolved mixture of several particulate substances.

Exemplary suitable organic containing solvents are selected from the group consisting of: an aqueous solution of water including a miscible amount of one or more miscible organic solvent(s); an organic solvent including a miscible amount of water; a pure organic solvent; a solution of two or more miscible organic solvents; and miscible combinations thereof. In general, essentially any of a wide variety of different organic solvents, and miscible combinations thereof, can be used for dissolving a given water insoluble electron transfer mediator. Solubility of a given water insoluble electron transfer mediator in a particular organic containing solvent is either known from prior art teachings, or is tested in a laboratory.

Exemplary water insoluble electron transfer mediators (catalysts) which are particularly applicable for implementing the method of the present invention, according to homogeneous catalysis, via a batch or flow mode, as described hereinabove and hereinbelow, are the previously described tetraphenylporphyrin-transition metal [5,10,15,20-tetraphenyl-21H,23H-porphine-transition metal] [TPP-transition metal] metalloporphyrin complexes, wherein, preferably, the transition metal is selected from the group consisting of cobalt [Co], nickel [Ni], iron [Fe], zinc [Zn], and copper [Cu]. These [TPP-transition metal] metalloporphyrin complexes are generally insoluble in pure or clean water, within the ranges of the above stated exemplary suitable conditions, and are either expected to be, or tested as being, insoluble, or at best, insufficiently soluble, in the contaminated water.

Thus, prior to exposure to the contaminated water, any one or more of the above indicated [TPP-transition metal] electron transfer mediators, singly or in combination, is/are dissolved in one of the above indicated exemplary suitable organic containing solvents, at suitable conditions (e.g., room temperature, with mixing), and then used in a solution form, i.e., as a solution of a dissolved single solid (typically, particulate) substance or as a solution of a dissolved mixture of several solid (typically, particulate) substances, for being exposed to the contaminated water.

The hereinabove described procedures for preparing particulate forms or/and solution forms of the catalytically effective amount of the at least one electron transfer mediator, are performed so that, upon exposing the contaminated water to the electron transfer mediator(s), each electron transfer mediator becomes freely mobile and soluble throughout the contaminated water, in order to form a batch or flow mode homogeneous catalytic reaction system as described hereinabove and hereinbelow.

Following preparation of the above described particulate forms or/and solution forms of the catalytically effective amount of the at least one electron transfer mediator, exposing the contaminated water thereto, according to homogeneous catalysis, via a batch or flow mode, is performed as described hereinbelow.

Batch Mode:

According to homogeneous catalysis, via a batch mode, any one or more of the hereinabove described particulate forms or/and solution forms of the catalytically effective amount of the at least one electron transfer mediator is/are added to a batch of a fixed or constant quantity (volume or mass) of the contaminated water. Alternatively, a batch of a fixed or constant quantity (volume or mass) of the contaminated water is added to any one or more particulate form or/and solution form of the catalytically effective amount of the at least one electron transfer mediator.

In each of these two exemplary specific preferred embodiments, the various homogeneous catalytic reaction processes take place within the batch of the contaminated water, for homogeneously catalytically treating that batch of the contaminated water. Such manners or ways of exposure are particularly performed for homogeneously catalytically treating batches of fixed or constant quantities of groundwater, surface water, above surface water, or a combination thereof, which are contaminated with the hereinabove described halogenated organic compounds. Moreover, such manners or ways of exposure can be used for operating batch types of homogeneous catalytic chemical reactors, which are clearly applicable for implementing the present invention.

Flow Mode:

According to homogeneous catalysis, via a flow mode, any one or more of the hereinabove described particulate forms or/and solution forms of the catalytically effective amount of the at least one electron transfer mediator is added to a (natural or/and forced) flow of the contaminated water. Alternatively, a (natural or/and forced) flow of the contaminated water is added to any one or more particulate form or/and a solution form of the catalytically effective amount of the at least one electron transfer mediator.

In each of these two exemplary specific preferred embodiments, the various homogeneous catalytic reaction processes take place within the flowing contaminated water, for homogeneously catalytically treating the flowing contaminated water. Such manners or ways of exposure are particularly performed for homogeneously catalytically treating flowing forms of groundwater, surface water, above surface water, or a combination thereof, which are contaminated with the hereinabove described halogenated organic compounds. Moreover, such manners or ways of exposure can be used for operating flow or fluidized types of homogeneous catalytic chemical reactors, which are clearly applicable for implementing the present invention.

Heterogeneous Catalysis:

For any of the hereinbelow described exemplary specific preferred manners or ways of exposing the contaminated water to the catalytically effective amount of the at least one electron transfer mediator, according to heterogeneous catalysis, via a batch or flow mode, the catalytically effective amount of the at least one electron transfer mediator is an initially solid (typically, particulate) substance that is supported, matrixed, intercalated, incorporated, or/and trapped, and generally immobile, on or/and inside of a (particulate or/and non-particulate) solid support or matrix material. Upon exposure to the contaminated water, the solid support or matrix material subsequently becomes dispersed (i.e., not dissolved) throughout the contaminated water. Ordinarily, the initially immobilized catalytically effective amount of the at least one electron transfer mediator similarly becomes dispersed (i.e., not dissolved) throughout the contaminated water. However, any one or more immobilized electron transfer mediator may at least partially dissolve in the contaminated water, depending upon actual parameters and conditions of a given heterogeneous catalytic chemical reaction system during implementation of the present invention.

Ordinarily, the entire catalytically effective amount of the at least one electron transfer mediator is used ‘as is’, in a particulate form, i.e., as a generally dry, single particulate substance or mixture of several particulate substances, of one or more electron transfer mediator solid supported or matrixed configurations. For implementing the method of the present invention, a specific example of such an electron transfer mediator solid supported or matrixed configuration is the hereinabove described diatomite/zero valent metal (ZVM)/electron transfer mediator composite type of heterogeneous catalyst.

Batch Mode:

According to heterogeneous catalysis, via a batch mode, any one or more of the hereinabove described electron transfer mediator solid supported or matrixed configurations of the catalytically effective amount of the at least one electron transfer mediator is/are added to a batch of a fixed or constant quantity (volume or mass) of the contaminated water. Alternatively, a batch of a fixed or constant quantity (volume or mass) of the contaminated water is added to any one or more electron transfer mediator solid supported or matrixed configuration of the catalytically effective amount of the at least one electron transfer mediator.

In each of these two exemplary specific preferred embodiments, the various heterogeneous catalytic reaction processes take place within the batch of the contaminated water, for heterogeneously catalytically treating that batch of the contaminated water. Such manners or ways of exposure are particularly performed for heterogeneously catalytically treating batches of fixed or constant quantities of groundwater, surface water, above surface water, or a combination thereof, which are contaminated with the hereinabove described halogenated organic compounds. Moreover, such manners or ways of exposure can be used for operating batch types of heterogeneous catalytic chemical reactors, which are clearly applicable for implementing the present invention.

Flow Mode:

According to heterogeneous catalysis, via a flow mode, any one or more of the hereinabove described electron transfer mediator solid supported or matrixed configurations of the catalytically effective amount of the at least one electron transfer mediator is/are added to a (natural or/and forced) flow of the contaminated water. Alternatively, a (natural or/and forced) flow of the contaminated water is added to any one or more electron transfer mediator solid supported or matrixed configuration of the catalytically effective amount of the at least one electron transfer mediator.

In each of these two exemplary specific preferred embodiments, the various heterogeneous catalytic reaction processes take place within the flowing contaminated water, for heterogeneously catalytically treating the flowing contaminated water. Such manners or ways of exposure are particularly performed for heterogeneously catalytically treating flowing forms of groundwater, surface water, above surface water, or a combination thereof, which are contaminated with the hereinabove described halogenated organic compounds. Moreover, such manners or ways of exposure can be used for operating flow or fluidized types of heterogeneous catalytic chemical reactors, which are clearly applicable for implementing the present invention.

Of particular interest in the field of environmental science and technology focusing on treating or remediating contaminated or polluted water, are the above exemplary specific preferred embodiments of implementing the method and system of the present invention according to heterogeneous catalysis, via a flow mode. In particular, including the use of any one or more of the hereinabove described electron transfer mediator solid supported or matrixed configurations of the catalytically effective amount of the at least one electron transfer mediator, for example, a diatomite/zero valent metal (ZVM)/electron transfer mediator composite type of heterogeneous catalyst which is contained within an in-situ unit (for example, as a groundwater permeable reactive barrier (PRB), or as part of a groundwater pumping and treatment system) located in the flowing contaminated water, or/and contained within an ex-situ unit (for example, a catalytic chemical reactor) which is physically situated or located, and operative, out of or away from the original site, place, or location, of the contaminated water, during the catalytic treatment (remediation, purification) process.

For implementing such a particular heterogeneous catalytic, flow mode, type of exemplary specific preferred embodiment of the method and system of the present invention, preferably, the manner or way of exposure is such that the (natural or/and forced) flow of the contaminated water, for example, in the form of flowing contaminated groundwater, surface water, above surface water, or a combination thereof, naturally or/and forcibly, is brought into physicochemical contact with, and, flows within and through, the electron transfer mediator solid supported or matrixed configuration while the electron transfer mediator solid supported or matrixed configuration remains contained by the in-situ or/and ex-situ unit.

Moreover, for implementing such a particular heterogeneous catalytic, flow mode, type of exemplary specific preferred embodiment of the method and system of the present invention, wherein the (natural or/and forced) flow of the contaminated water is specifically in the form of flowing contaminated groundwater (e.g., a sub-surface water region, reservoir, or aquifer), preferably, the manner or way of exposure is such that the volumetric flow rate of the (natural or/and forced) flow of the contaminated water which naturally or/and forcibly flows within and through the contained electron transfer mediator solid supported or matrixed configuration is at least equal to or larger than the volumetric flow rate of the (natural or/and forced) flow of the contaminated water which naturally or/and forcibly flows through the ground or material immediately surrounding the contained electron transfer mediator solid supported or matrixed configuration. Accordingly, preferably, the manner or way of exposure is such that the permeability (to the flowing contaminated groundwater) of the contained electron transfer mediator solid supported or matrixed configuration is at least equal to or larger than the permeability (to the flowing contaminated groundwater) of the ground or material immediately surrounding the contained electron transfer mediator solid supported or matrixed configuration.

The preceding described heterogeneous catalytic, flow mode, types of exemplary specific preferred embodiments of implementing the method and system of the present invention, are particularly applicable to a variety of different exemplary specific preferred embodiments of the system (further described hereinbelow and illustrated in FIGS. 4-7), wherein the electron transfer mediator solid supported or matrixed configuration is contained within at least one (in-situ or/and ex-situ) unit located at one or more positions of an overall system used for processing or treating the contaminated water.

Reducing Conditions in the Contaminated Water:

For each of the above exemplary specific preferred embodiments of implementing the method and system of the present invention according to homogeneous catalysis, via a batch or flow mode, or/and according to heterogeneous catalysis, via a batch or flow mode, exposing the contaminated water to the catalytically effective amount of the at least one electron transfer mediator is performed under reducing (anaerobic or anoxic) conditions, i.e., when reducing conditions, as opposed to oxidizing conditions, are prevalent in and throughout the contaminated water being treated.

As is well known in the relevant art of the present invention, for example, as relating to redox (reduction-oxidation) chemical reactions, in general, and reductive dehalogenation, in particular, the phrase ‘reducing conditions’ generally refers to the existence or presence of conditions wherein an energy source of at least part of a redox (reduction-oxidation) chemical reaction phenomenon, mechanism, or/and process, is derived from electrochemical reduction of one or more (relatively oxidized) substances (chemical species). Common examples of reducing conditions which are especially prevalent in aqueous environments, such as contaminated water being in a form of groundwater (e.g., sub-surface water regions, reservoirs, or aquifers), surface water (e.g., rivers, lakes, ponds, pools, or surface water reservoirs), above surface water (e.g., above surface water reservoirs, or above surface sources or supplies of residential or commercial drinking water), or a combination thereof, are nitrate reducing conditions, manganogenic reducing conditions, ferrogenic reducing conditions, sulfidogenic reducing conditions, and methanogenic reducing conditions. Each example of reducing conditions refers to the existence or presence of conditions wherein an energy source of at least part of a redox chemical reaction phenomenon, mechanism, or/and process, is derived from electrochemical reduction of one or more of the corresponding (relatively oxidized) substances (chemical species), singly or in combination. In particular, one or more of (relatively oxidized) substances (chemical species) containing nitrate [NO₃ ⁻] or nitrate [NO₃], or/and manganese (e.g., as Mn⁺⁴) or manganese [Mn], or/and iron (e.g., as Fe⁺³ or Fe⁺²) or iron [Fe], or/and sulfate [SO₄ ⁻²] or sulfate [SO₄], or/and carbon dioxide [CO₂] or carbon dioxide, respectively.

In aqueous environments, such as contaminated water being in a form of groundwater, surface water, above surface water, or a combination thereof, ‘oxidizing conditions’, generally referring to the existence or presence of conditions wherein an energy source of at least part of a redox (reduction-oxidation) chemical reaction phenomenon, mechanism, or/and process, is derived from electrochemical oxidation of one or more (relatively reduced) substances (chemical species), are based on the existence or presence, and reaction, of dissolved free (unreacted) molecular oxygen [O₂] in the contaminated water. Dissolved oxygen [O₂] types of oxidation driven redox chemical reactions which require, and take place under, oxidizing conditions, are usually, significantly thermodynamically favored compared to reduction driven redox chemical reactions which require, and take place under, reducing conditions. However, in such aqueous environments, demand and consumption of dissolved free (unreacted) molecular oxygen are usually very large and fast. Depletion of the free (unreacted) molecular oxygen naturally, eventually leads to the prevalence of the above described reducing conditions, in such aqueous environments.

For implementing the method and system of the present invention, reducing conditions, as described above, naturally exist, or/and are anthropogenically (human) produced, in the contaminated water. When reducing conditions are naturally prevalent in the contaminated water, and are considered sufficient for effectively enabling the phenomena, mechanisms, and processes, of the electron transfer mediated (homogeneous or heterogeneous) catalytic reductive dehalogenation reactions, for catalyzing reductive dehalogenation of the halogenated organic compound contaminants in the contaminated water, then, ordinarily, there is no need for anthropogenically producing the reducing conditions in the contaminated water. However, when reducing conditions are not naturally prevalent in the contaminated water, or are considered insufficient for effectively enabling the phenomena, mechanisms, and processes, of the electron transfer mediated (homogeneous or heterogeneous) catalytic reductive dehalogenation reactions, for catalyzing reductive dehalogenation of the halogenated organic compound contaminants in the contaminated water, then, ordinarily, there is need for anthropogenically producing the reducing conditions in the contaminated water. Accordingly, in the latter instance, the method and system of the present invention further includes a procedure for anthropogenically producing reducing conditions in the contaminated water.

Bulk Electron Donors or Reducing Agents:

Anthropogenically producing the reducing conditions in the contaminated water is performed by exposing the contaminated water to at least one bulk electron donor or reducing agent, immediately before, or/and during, or/and immediately after, exposing the contaminated water to the catalytically effective amount of the at least one electron transfer mediator. Alternatively, anthropogenically producing the reducing conditions in the contaminated water is performed by using an electron transfer mediator solid supported or matrixed configuration type of heterogeneous catalyst that already includes at least one bulk electron donor or reducing agent as part of the heterogeneous catalyst structure or composition, such as the above described diatomite/zero valent metal (ZVM)/electron transfer mediator composite type of heterogeneous catalyst.

In general, essentially any bulk electron donor or reducing agent capable of reducing an electron transfer mediator under reducing (anaerobic or anoxic) conditions can be used for implementing the method and system of the present invention. In general, any or all of the at least one bulk electron donor or reducing agent is/are soluble or insoluble in the contaminated water. In particular, among the following indicated bulk electron donors or reducing agents, ordinarily, the elemental metals are insoluble in the contaminated water, whereas the compounds are soluble in the contaminated water.

Preferably, the at least one bulk electron donor or reducing agent includes an elemental metal (zero valent metal). Preferably, the bulk electron donor or reducing agent elemental metal (zero valent metal) is selected from the group consisting of iron [Fe⁰], lithium [Li⁰], sodium [Na⁰], potassium [K⁰], beryllium [Be⁰], magnesium [Mg⁰], titanium [Ti⁰], and any mixture thereof. Alternatively, the bulk electron donor or reducing agent compounds is selected from the group consisting of titanium (III) citrate [Ti(OC(CH₂COOH)₂COOH], potassium borohydride [KBH₄], sodium borohydride [NaBH₄], lithium hydride [LiH], potassium hydride [KaH], sodium hydride [NaH], borotrihydride [BH₃], aluminum trihydride [AlH₃], hydrazine [H₂NNH₂], triphenylphosphate [PPh₃], sodium dithionite (sodium hydrosulfite) [Na₂S₂O₄], and any combination thereof.

In general, the quantity of the at least one bulk electron donor or reducing agent to which the contaminated water is exposed can be varied. The quantity of the at least one bulk electron donor or reducing agent to which the contaminated water is exposed, expressed in terms of a molar concentration, corresponds to the number of moles of the at least one bulk electron donor or reducing agent per unit volume (for example, liter) of the contaminated water, and is written as moles bulk electron donor or reducing agent per liter contaminated water. The quantity of the at least one bulk electron donor or reducing agent to which the contaminated water is exposed, in terms of a molar concentration, is in a range of, preferably, between about 10⁻⁴ and about 1.0 mole bulk electron donor or reducing agent per liter contaminated water, and more preferably, between about 10⁻³ and about 10⁻¹ mole bulk electron donor or reducing agent per liter contaminated water. The optimum quantity of the at least one bulk electron donor or reducing agent to which the contaminated water is exposed, in terms of a molar concentration, is about 10⁻² mole bulk electron donor or reducing agent per liter contaminated water.

Exposing the Contaminated Water to the Bulk Electron Donor(s) or Reducing Agent(s):

For anthropogenically producing the reducing conditions in the contaminated water, in general, exposing the contaminated water to the at least one bulk electron donor or reducing agent is performed according to any of a variety of different manners or ways well known in the art, which are compatible for forming the previously hereinabove described batch mode or flow mode, homogeneous or heterogeneous, catalytic reaction systems. As stated hereinabove, for implementing the method and system of the present invention, there is exposing the contaminated water to at least one bulk electron donor or reducing agent, immediately before, or/and during, or/and immediately after, exposing the contaminated water to the catalytically effective amount of the at least one electron transfer mediator. The actual manner or way of exposing the contaminated water to at least one bulk electron donor or reducing agent, that is, immediately before, or/and during, or/and immediately after, exposing the contaminated water to the catalytically effective amount of the at least one electron transfer mediator, is determined according to, and compatible with, the previously hereinabove described exemplary specific preferred embodiments of implementing the method of the present invention according to homogeneous catalysis, via a batch or flow mode, or, according to heterogeneous catalysis, via a batch or flow mode.

For example, for implementing the method and system of the present invention according to homogeneous catalysis, or according to heterogeneous catalysis, each via a batch mode, the at least one bulk electron donor or reducing agent is added to a batch of a fixed or constant quantity (volume or mass) of the contaminated water, immediately before, or/and during, or/and immediately after, exposing the batch of the contaminated water to the catalytically effective amount of the at least one electron transfer mediator. Alternatively, a batch of a fixed or constant quantity (volume or mass) of the contaminated water is added to the at least one bulk electron donor or reducing agent, immediately before, or/and during, or/and immediately after, exposing the batch of the contaminated water to the catalytically effective amount of the at least one electron transfer mediator.

For example, for implementing the method and system of the present invention according to homogeneous catalysis, or according to heterogeneous catalysis, each via a flow mode, the at least one bulk electron donor or reducing agent is added to a (natural or/and forced) flow of the contaminated water, immediately before, or/and during, or/and immediately after, exposing the flow of the contaminated water to the catalytically effective amount of the at least one electron transfer mediator. Alternatively, a (natural or/and forced) flow of the contaminated water is added to the at least one bulk electron donor or reducing agent, immediately before, or/and during, or/and immediately after, exposing the flow of the contaminated water to the catalytically effective amount of the at least one electron transfer mediator.

Preferably, the reducing conditions naturally exist, or/and are anthropogenically produced, in the contaminated water, such that only the halogenated organic compound contaminant species in the contaminated water, and not non-contaminant species (such as oxygen gas) which may be present in the contaminated water or/and in the immediate vicinity of the contaminated water, are catalytically reduced by the at least one electron transfer mediator (catalyst).

Extent of Time or Duration of the Catalytic Reductive Dehalogenation Reaction(s):

In general, for each of the above exemplary specific preferred embodiments of implementing the method and system of the present invention, the extent of time or duration (for example, hours, days, weeks, etc.) of exposing the contaminated water to the catalytically effective amount of the at least one electron transfer mediator, under reducing conditions, depends upon the hereinabove described primary, secondary, and tertiary, parameters of a given batch or flow mode homogeneous or heterogeneous catalytic reaction system. In particular, as relating to the types, quantities, concentrations, and, physicochemical properties, characteristics, and behavior, of the targeted (known or/and suspected) halogenated organic compound contaminants in the contaminated water, and of the catalytically effective amount of the at least one electron transfer mediator, and, as relating to the bulk quantity, and, physicochemical and hydrodynamic (flow) properties, characteristics, and behavior, and form, of the contaminated water, for example, as groundwater (e.g., sub-surface water region, reservoir, or aquifer), as surface water (e.g., river, lake, pond, pool, or surface water reservoir), as above surface water (e.g., above surface water reservoir, or above surface source or supply of residential or commercial drinking water), or as a combination thereof.

As stated hereinabove, the system for catalytically treating water contaminated with halogenated organic compounds, wherein the halogenated organic compounds are selected from the group consisting of chlorotriazine herbicides, chloroacetanilide herbicides, halogenated aliphatic herbicides, halogen containing analogs thereof, halogen containing derivatives thereof, and combinations thereof, of the present invention, includes the following main components and functionalities thereof: (a) at least one electron transfer mediator; and (b) at least one (in-situ or/and ex-situ) unit for containing a catalytically effective amount of the at least one electron transfer mediator, for exposing the contaminated water to the at least one electron transfer mediator under reducing conditions. Use of the system of the present invention results in decreasing the concentration of at least one of the halogenated organic compounds in the contaminated water.

For implementing the method and system of the present invention, an in-situ unit is essentially physically (spatially) situated or located, and operative, at or within the actual site, place, or location, of the contaminated water, during the catalytic treatment (remediation, purification) process. Accordingly, an in-situ unit is in hydrodynamic communication with the contaminated water by means associated with, and corresponding to, the coinciding (generally same) physical (spatial) locations of the in-situ unit and the contaminated water. An ex-situ unit is essentially physically (spatially) situated or located, and operative, out of or away from the actual site, place, or location, of the contaminated water, during the catalytic treatment (remediation, purification) process. Accordingly, an ex-situ unit is in hydrodynamic communication with the contaminated water by means associated with, and corresponding to, the non-coinciding (generally separate) physical (spatial) locations of the ex-situ unit and the contaminated water.

Reference is again made to FIGS. 4-7, wherein are shown exemplary applicable in-situ and ex-situ units for containing the catalytically effective amount of the at least one electron transfer mediator as a heterogeneous catalyst. An in-situ unit is in a form as at least part of a groundwater permeable reactive barrier (PRB) configured as a continuous filled in trench or wall (for example, in-situ unit 20 (FIG. 4)), or as a stand-alone filled in well (for example, in-situ units 30 (FIG. 5)), or in a form as part of a groundwater pumping and treatment system (for example, in-situ unit 32 (FIG. 6)). An exemplary applicable ex-situ unit for containing the catalytically effective amount of the at least one electron transfer mediator as a homogeneous catalyst or/and as a heterogeneous catalyst is in a form as part of an above surface water treatment reactor system (for example, ex-situ unit 48 (FIG. 7)).

As used herein, consistent with that taught about and used in the art of contaminated groundwater treatment (remediation, purification), a permeable reactive barrier (PRB) means a closed or open structure or configuration, such as a filled in trench, wall, or stand-alone well, or a system of several closed or/and open structures or configurations, that provides passive interception and in-situ treatment of contaminated groundwater. A permeable reactive barrier is characterized by having a permeable zone containing or creating a reactive treatment area, including a highly reactive material, for example, the catalytically effective amount of the at least one electron transfer mediator (as a heterogeneous catalyst) as part of a (particulate or/and non-particulate) solid support or matrix material, and optionally, also including a less reactive, or/and an inactive, or/and a non-reactive material, oriented to intercept and remediate or purify a groundwater contaminant plume (i.e., a specific groundwater region or zone concentrated with contaminants), by direct exposure of the contaminants to the reactive material.

Ideally, a PRB provides a preferential flow path of the contaminated groundwater through the reactive material, and the other possibly present materials, and serves as a medium for the catalytic degradation, transformation, or conversion, of the halogenated organic compounds in the contaminated water to non-hazardous or/and less hazardous chemical species which exit the barrier, while minimally disrupting natural flow of the groundwater. Typically, the contaminated groundwater flows by natural flow (pressure or current) gradients through the PRB, however, pumping schemes configured upstream, within, or/and downstream, the PRB, can also be used for implementing a PRB setup. A PRB can be installed as a permanent or semi-permanent unit spanning along or/and across the flow path of a contaminant plume. Alternatively, a PRB can be installed as a construction or configuration as part of an in-situ reactor which is readily accessible to facilitate the removal or/and replacement of the spent (deactivated) reactive catalyst material, and the other possibly present materials.

FIG. 4 is a schematic diagram illustrating a cut-away view of exemplary specific preferred embodiments of implementing the method and system of the present invention according to heterogeneous catalysis, via a flow mode, as described hereinabove. The contaminated water is in the form of a natural flow of groundwater, and the catalytically effective amount of the at least one electron transfer mediator (as a heterogeneous catalyst) is part of a (particulate or/and non-particulate) solid support or matrix material dispersed throughout and contained within an in-situ unit being in a form as the lower portion of a groundwater permeable reactive barrier (PRB) configured as a continuous filled in trench or wall.

As shown in FIG. 4, groundwater 10, contaminated with any type and number of the hereinabove illustratively described halogenated organic compound contaminants 12 (indicated in 10 by the filled in irregularly shaped forms), naturally flows (indicated in 10 by the arrows pointing toward the right direction) between underground regions 14, located beneath top surface region 16. A catalytically effective amount of the at least one electron transfer mediator (as a heterogeneous catalyst) 18 is dispersed throughout and contained within an in-situ unit 20 being in a form as the lower portion of a permeable reactive barrier (PRB) 22 configured as a continuous filled in trench or wall, whose upper portion 24 is filled with an inactive or/and a non-reactive filler material 26.

In-situ unit 20 is structured and functions for containing the catalytically effective amount of the at least one electron transfer mediator 18, and for enabling the exposing of the natural flow of contaminated groundwater (10 plus 12) to the catalytically effective amount of the at least one electron transfer mediator 18, under reducing (anaerobic or anoxic) conditions. Moreover, in-situ unit 20 is structured and functions according to heterogeneous catalysis, via a flow mode. The various heterogeneous catalytic reaction processes take place within the flowing contaminated groundwater (10 plus 12), for heterogeneously catalytically treating the flowing contaminated groundwater (10 plus 12), to thereby decrease the concentration of at least one of halogenated organic compound contaminants 12 in contaminated groundwater (10 plus 12). Accordingly, flowing groundwater 10 exiting (to the right of) in-situ unit 20 has been catalytically treated (remediated or purified) with respect to a decrease in concentration of at least one of halogenated organic compound contaminants 12.

FIG. 5 is a schematic diagram illustrating a cut-away view of exemplary specific preferred embodiments of implementing the method and system of the present invention according to heterogeneous catalysis, via a flow mode, as described hereinabove. The contaminated water is in the form of a natural flow of groundwater, and the catalytically effective amount of the at least one electron transfer mediator (as a heterogeneous catalyst) is part of a (particulate or/and non-particulate) solid support or matrix material dispersed throughout and contained within each of a plurality of in-situ units each being in a form as a groundwater permeable reactive barrier (PRB) configured as a stand-alone filled in well.

As shown in FIG. 5, groundwater 10, contaminated with any type and number of the hereinabove illustratively described halogenated organic compound contaminants 12, naturally flows (indicated in 10 by the arrows pointing toward the right direction) between underground regions 14, located beneath top surface region 16. A catalytically effective amount of the at least one electron transfer mediator (as a heterogeneous catalyst) 18 is dispersed throughout and contained within each of a plurality of (for example, six) in-situ units 30 each being in a form as a groundwater permeable reactive barrier (PRB) configured as a stand-alone filled in well.

Each of the in-situ units 30 is structured and functions for containing the catalytically effective amount of the at least one electron transfer mediator 18, and for enabling the exposing of the natural flow of contaminated groundwater (10 plus 12) to the catalytically effective amount of the at least one electron transfer mediator 18, under reducing (anaerobic or anoxic) conditions. Moreover, each of the in-situ units 30 is structured and functions according to heterogeneous catalysis, via a flow mode. The various heterogeneous catalytic reaction processes take place within the flowing contaminated groundwater (10 plus 12), for heterogeneously catalytically treating the flowing contaminated groundwater (10 plus 12), to thereby decrease the concentration of at least one of halogenated organic compound contaminants 12 in contaminated groundwater (10 plus 12). Accordingly, flowing groundwater 10 exiting (to the right of) in-situ units 30 has been catalytically treated (remediated or purified) with respect to a decrease in concentration of at least one of halogenated organic compound contaminants 12.

FIG. 6 is a schematic diagram illustrating a cut-away view of exemplary specific preferred embodiments of implementing the method and system of the present invention according to heterogeneous catalysis, via a flow mode, as described hereinabove. The contaminated water is in the form of a natural and forced flow of groundwater, and the catalytically effective amount of the at least one electron transfer mediator (as a heterogeneous catalyst) is part of a (particulate or/and non-particulate) solid support or matrix material dispersed throughout and contained within an in-situ unit being in a form as part of a groundwater pumping and treatment system.

As shown in FIG. 6, groundwater 10, contaminated with any type and number of the hereinabove illustratively described halogenated organic compound contaminants 12, in addition to any possible natural flow (indicated in 10 by the single arrow pointing towards the right direction), forcibly flows, via pumping by a water pumping device 36, (indicated in 10 by the two sets of arrows each pointing towards water pumping device 36) between underground regions 14, located beneath top surface region 16. A catalytically effective amount of the at least one electron transfer mediator (as a heterogeneous catalyst) 18 is dispersed throughout and contained within an in-situ unit 32 being in a form as the middle part of a groundwater pumping and treatment system (36, 32, and 40).

Contaminated groundwater (10 plus 12) is pumped and forcibly flows, into and through the volume and contents 34 of water pumping device 36, via pumping by water pumping device 36 located at the lower portion of groundwater pumping and treatment system (36, 32, and 40). Contaminated groundwater (10 plus 12) is then pumped and forcibly flows upward, into, and through, the catalytically effective amount of the at least one electron transfer mediator (as a heterogeneous catalyst) 18 contained within in-situ unit 32 located in the middle portion of groundwater pumping and treatment system (36, 32, and 40). Catalytically treated (remediated or purified) groundwater 10 is then pumped and forcibly flows upward, into, and through, the volume and contents 38 of a treated water collection/passage chamber 40 located in the upper portion of groundwater pumping and treatment system (36, 32, and 40). The catalytically treated groundwater 10 then exits through the top portion of treated water collection/passage chamber 40, as indicated by 42.

In-situ unit 32 is structured and functions for containing the catalytically effective amount of the at least one electron transfer mediator 18, and for enabling the exposing of the natural and forced flow of contaminated groundwater (10 plus 12) to the catalytically effective amount of the at least one electron transfer mediator 18, under reducing (anaerobic or anoxic) conditions. Moreover, in-situ unit 32 is structured and functions according to heterogeneous catalysis, via a flow mode. The various heterogeneous catalytic reaction processes take place within the flowing contaminated groundwater (10 plus 12), for heterogeneously catalytically treating the flowing contaminated groundwater (10 plus 12), to thereby decrease the concentration of at least one of halogenated organic compound contaminants 12 in contaminated groundwater (10 plus 12). Accordingly, flowing groundwater 42 exiting through the top portion of treated water collection/passage chamber 40 has been catalytically treated (remediated or purified) with respect to a decrease in concentration of at least one of halogenated organic compound contaminants 12.

FIG. 7 is a schematic diagram illustrating a cut-away view of three exemplary specific configurations, of exemplary specific preferred embodiments of implementing the method and system of the present invention according to homogeneous or/and heterogeneous catalysis, via a batch or flow mode, as described hereinabove. The contaminated water is in the form(s) of natural or/and forced flow of groundwater, surface water, or/and above surface water. The catalytically effective amount of the at least one electron transfer mediator is a homogeneous catalyst in a water soluble particulate form or/and aqueous solution form contained within an ex-situ unit, or/and is a heterogeneous catalyst as part of a (particulate or/and non-particulate) solid support or matrix material dispersed throughout and contained within an ex-situ unit, wherein the ex-situ unit is in a form as part of an above surface water treatment reactor system.

First Configuration:

According to the first configuration shown in FIG. 7, groundwater 10, for example, of a sub-surface water region, reservoir, or aquifer, contaminated with any type and number of the hereinabove illustratively described halogenated organic compound contaminants 12, in addition to any possible natural flow (indicated in 10 by the single arrow pointing towards the right direction), forcibly flows, via pumping by a water pumping device 46, (indicated in 10 by the two sets of arrows each pointing towards water pumping device 46) between underground regions 14, located beneath top surface region 16.

In the first configuration, either part of, or the entire, catalytically effective amount of the at least one electron transfer mediator is a homogeneous catalyst 18 in a water soluble particulate form or/and aqueous solution form is contained within an ex-situ unit 48 being in a form as part of an above surface water treatment reactor system 50. In this case, ex-situ unit 48 is structured and functions according to homogeneous catalysis, via a batch mode or via a flow mode. Alternatively, or additionally, either part of, or the entire, catalytically effective amount of the at least one electron transfer mediator is a heterogeneous catalyst 18 as part of a (particulate or/and non-particulate) solid support or matrix material dispersed throughout and contained within an ex-situ unit 48 being in a form as part of an above surface water treatment reactor system 50. In this case, ex-situ unit 48 is structured and functions according to heterogeneous catalysis, via a batch mode or via a flow mode.

Contaminated groundwater (10 plus 12) is pumped and forcibly flows, into and through the volume and contents 44 of water pumping device 46, from water pumping device 46, via a water transport line (pipe) 52, into ex-situ unit 48 of above surface water treatment reactor system 50, and is then exposed to the homogeneous form or/and heterogeneous form of catalytically effective amount of the at least one electron transfer mediator catalyst 18. Catalytically treated (remediated or purified) groundwater 10 then exits out of above surface water treatment reactor system 50, as indicated by 54.

Ex-situ unit 48 is structured and functions for containing the homogeneous form or/and heterogeneous form of the catalytically effective amount of the at least one electron transfer mediator 18, and for enabling the exposing of the natural and forced flow of contaminated groundwater (10 plus 12) to the homogeneous form or/and heterogeneous form of the catalytically effective amount of the at least one electron transfer mediator 18, under reducing (anaerobic or anoxic) conditions. Moreover, ex-situ unit 48 is structured and functions according to homogeneous or/and heterogeneous catalysis, via a batch or flow mode. The various homogeneous or/and heterogeneous catalytic reaction processes take place within a batch or flow of the contaminated groundwater (10 plus 12), for homogeneously or/and heterogeneously catalytically treating the flowing contaminated groundwater (10 plus 12), to thereby decrease the concentration of at least one of halogenated organic compound contaminants 12 in contaminated groundwater (10 plus 12). Accordingly, groundwater 54 exiting out of above surface water treatment reactor system 50 has been catalytically treated (remediated or purified) with respect to a decrease in concentration of at least one of halogenated organic compound contaminants 12.

Second Configuration:

According to the second configuration shown in FIG. 7, surface water 56, for example, of a river, lake, pond, pool, or surface water reservoir, herein, generally indicated as 58, contaminated with any type and number of the hereinabove illustratively described halogenated organic compound contaminants 12, is located along top surface region 16.

In the second configuration, either part of, or the entire, catalytically effective amount of the at least one electron transfer mediator is a homogeneous catalyst 18 in a water soluble particulate form or/and aqueous solution form contained within an ex-situ unit 48 being in a form as part of an above surface water treatment reactor system 50. In this case, ex-situ unit 48 is structured and functions according to homogeneous catalysis, via a batch mode or via a flow mode. Alternatively, or additionally, either part of, or the entire, catalytically effective amount of the at least one electron transfer mediator is a heterogeneous catalyst 18 as part of a (particulate or/and non-particulate) solid support or matrix material dispersed throughout and contained within an ex-situ unit 48 being in a form as part of an above surface water treatment reactor system 50. In this case, ex-situ unit 48 is structured and functions according to heterogeneous catalysis, via a batch mode or via a flow mode.

Contaminated surface water (56 plus 12), in addition to any possible natural flow (indicated in 56 by the two arrows pointing toward the right direction), is pumped and forcibly flows, from river, lake, pond, pool, or surface water reservoir, 58, via a water transport line (pipe) 60, into ex-situ unit 48 of above surface water treatment reactor system 50, and is then exposed to the homogeneous form or/and heterogeneous form of catalytically effective amount of the at least one electron transfer mediator catalyst 18. Catalytically treated (remediated or purified) surface water 56 then exits out of above surface water treatment reactor system 50, as indicated by 54.

Ex-situ unit 48 is structured and functions for containing the homogeneous form or/and heterogeneous form of the catalytically effective amount of the at least one electron transfer mediator 18, and for enabling the exposing of the natural and forced flow of contaminated surface water (56 plus 12) to the homogeneous form or/and heterogeneous form of the catalytically effective amount of the at least one electron transfer mediator 18, under reducing (anaerobic or anoxic) conditions. Moreover, ex-situ unit 48 is structured and functions according to homogeneous or/and heterogeneous catalysis, via a batch or flow mode. The various homogeneous or/and heterogeneous catalytic reaction processes take place within a batch or flow of the contaminated surface water (56 plus 12), for homogeneously or/and heterogeneously catalytically treating the flowing contaminated surface water (56 plus 12), to thereby decrease the concentration of at least one of halogenated organic compound contaminants 12 in contaminated surface water (56 plus 12). Accordingly, surface water 56 exiting out of above surface water treatment reactor system 50 has been catalytically treated (remediated or purified) with respect to a decrease in concentration of at least one of halogenated organic compound contaminants 12.

Third Configuration:

According to the third configuration shown in FIG. 7, above surface water 62, for example, of an above surface water reservoir, or of an above surface source or supply of residential or commercial drinking water, herein, generally indicated as 64, contaminated with any type and number of the hereinabove illustratively described halogenated organic compound contaminants 12 (present, but not indicated, in 62, in FIG. 7) is located on and above top surface region 16.

In the third configuration, either part of, or the entire, catalytically effective amount of the at least one electron transfer mediator is a homogeneous catalyst 18 in a water soluble particulate form or/and aqueous solution form contained within an ex-situ unit 48 being in a form as part of an above surface water treatment reactor system 50. In this case, ex-situ unit 48 is structured and functions according to homogeneous catalysis, via a batch mode or via a flow mode. Alternatively, or additionally, either part of, or the entire, catalytically effective amount of the at least one electron transfer mediator is a heterogeneous catalyst 18 as part of a (particulate or/and non-particulate) solid support or matrix material dispersed throughout and contained within an ex-situ unit 48 being in a form as part of an above surface water treatment reactor system 50. In this case, ex-situ unit 48 is structured and functions according to heterogeneous catalysis, via a batch mode or via a flow mode.

Contaminated above surface water (62 plus 12) is pumped and forcibly flows, from above surface water reservoir, or above surface source or supply of residential or commercial drinking water, 64, via a water transport line (pipe) 66, into ex-situ unit 48 of above surface water treatment reactor system 50, and is then exposed to the homogeneous form or/and heterogeneous form of catalytically effective amount of the at least one electron transfer mediator catalyst 18. Catalytically treated (remediated or purified) above surface water 62 then exits out of above surface water treatment reactor system 50, as indicated by 54.

Ex-situ unit 48 is structured and functions for containing the homogeneous form or/and heterogeneous form of the catalytically effective amount of the at least one electron transfer mediator 18, and for enabling the exposing of the natural and forced flow of contaminated above surface water (62 plus 12) to the homogeneous form or/and heterogeneous form of the catalytically effective amount of the at least one electron transfer mediator 18, under reducing (anaerobic or anoxic) conditions. Moreover, ex-situ unit 48 is structured and functions according to homogeneous or/and heterogeneous catalysis, via a batch or flow mode. The various homogeneous or/and heterogeneous catalytic reaction processes take place within a batch or flow of the contaminated above surface water (62 plus 12), for homogeneously or/and heterogeneously catalytically treating the flowing contaminated above surface water (62 plus 12), to thereby decrease the concentration of at least one of halogenated organic compound contaminants 12 in contaminated above surface water (62 plus 12). Accordingly, above surface water 62 exiting out of above surface water treatment reactor system 50 has been catalytically treated (remediated or purified) with respect to a decrease in concentration of at least one of halogenated organic compound contaminants 12.

It is noted that for each of the above described exemplary specific preferred embodiments of implementing the method and system of the present invention, as illustrated in FIGS. 4-7, according to homogeneous catalysis, via a batch or flow mode, or/and according to heterogeneous catalysis, via a batch or flow mode, exposing the contaminated water to the catalytically effective amount of the at least one electron transfer mediator is performed under reducing (anaerobic or anoxic) conditions, i.e., when reducing conditions, as opposed to oxidizing conditions, are prevalent in and throughout the contaminated water being treated.

Reducing conditions, as previously described hereinabove, naturally exist, or/and are anthropogenically (human) produced, in the contaminated water. When reducing conditions are naturally prevalent in the contaminated water, and are considered sufficient for effectively enabling the phenomena, mechanisms, and processes, of the electron transfer mediated (homogeneous or heterogeneous) catalytic reductive dehalogenation reactions, for catalyzing reductive dehalogenation of the halogenated organic compound contaminants in the contaminated water, then, ordinarily, there is no need for anthropogenically producing the reducing conditions in the contaminated water. However, when reducing conditions are not naturally prevalent in the contaminated water, or are considered insufficient for effectively enabling the phenomena, mechanisms, and processes, of the electron transfer mediated (homogeneous or heterogeneous) catalytic reductive dehalogenation reactions, for catalyzing reductive dehalogenation of the halogenated organic compound contaminants in the contaminated water, then, ordinarily, there is need for anthropogenically producing the reducing conditions in the contaminated water. Accordingly, in the latter instance, any of the above described exemplary specific preferred embodiments of implementing the method and system of the present invention, as illustrated in FIGS. 4-7, further includes a procedure for anthropogenically producing reducing conditions in the contaminated water.

As previously described hereinabove, anthropogenically producing the reducing conditions in the contaminated water is performed by exposing the contaminated water to at least one bulk electron donor or reducing agent, immediately before, or/and during, or/and immediately after, exposing the contaminated water to the catalytically effective amount of the at least one electron transfer mediator. Alternatively, anthropogenically producing the reducing conditions in the contaminated water is performed by using an electron transfer mediator solid supported or matrixed configuration type of heterogeneous catalyst that already includes at least one bulk electron donor or reducing agent as part of the heterogeneous catalyst structure or composition, such as the above described diatomite/zero valent metal (ZVM)/electron transfer mediator composite type of heterogeneous catalyst.

The actual manner or way of exposing the contaminated water to at least one bulk electron donor or reducing agent, that is, immediately before, or/and during, or/and immediately after, exposing the contaminated water to the catalytically effective amount of the at least one electron transfer mediator, is determined according to, and compatible with, the previously hereinabove described exemplary specific preferred embodiments of implementing the method of the present invention according to homogeneous catalysis, via a batch or flow mode, or, according to heterogeneous catalysis, via a batch or flow mode.

In general, for any of the above described exemplary specific preferred embodiments of implementing the method and system of the present invention, as illustrated in FIGS. 4-7, according to heterogeneous catalysis, via a batch or flow mode, following heterogeneous catalytic treatment of the contaminated water, the electron transfer mediator solid supported or matrixed configuration type heterogeneous catalyst 18 can be removed from the associated in-situ unit(s) (for example, in-situ unit 20 (FIG. 4), in-situ units 30 (FIG. 5), in-situ unit 32 (FIG. 6)), ex-situ unit (for example, ex-situ unit 48 (FIG. 7)) used for treating the contaminated water, and be recycled for again treating the contaminated water. Such recycling can include, for example, subjecting the electron transfer mediator solid supported or matrixed configuration type heterogeneous catalyst 18 to a cleaning procedure, involving selective removal of the adsorbed contaminants from the solid support or matrix, while non-destructively handling and processing the solid support or matrix.

The hereinabove illustratively described method and system of the present invention are particularly applicable for catalytically treating water contaminated with halogenated organic compounds, wherein the halogenated organic compounds are selected from the group consisting of chlorotriazine herbicides, chloroacetanilide herbicides, halogenated aliphatic herbicides, halogen containing analogs thereof, halogen containing derivatives thereof, and combinations thereof. Nevertheless, the method and system of the present invention are generally applicable for catalytically treating water contaminated with other types or kinds of halogenated organic compounds, not limited to being halogenated organic herbicides, halogen containing analogs thereof, or halogen containing derivatives thereof.

Above illustratively described novel and inventive aspects and characteristics, and advantages thereof, of the present invention further become apparent to one ordinarily skilled in the art upon examination of the following examples, which are not intended to be limiting. Additionally, each of the various embodiments and aspects of the present invention as delineated herein above and as claimed in the claims section below finds experimental support in the following examples.

EXAMPLES

Reference is now made to the following examples, Examples 1-4, which together with the above description, illustrate the invention in a non-limiting fashion.

Atrazine [C₈H₁₄ClN₅] is among the most well known exemplary chlorinated organonitrogen herbicide (CONH) types of halogenated organic herbicide members of the chlorotriazine herbicide group (FIG. 1). As discussed hereinabove in the Background section, atrazine, and halogen (in particular, chlorine) containing degradation products thereof, are among the most widely used agricultural chemicals (agrochemicals), and are among the most pervasive, persistent, proven or potentially hazardous (poisonous or toxic), undesirable contaminants or pollutants in various forms of water, such as groundwater (e.g., sub-surface water regions, reservoirs, or aquifers), surface water (e.g., rivers, lakes, ponds, pools, or surface water reservoirs), above surface water (e.g., above surface water reservoirs, or above surface sources or supplies of residential or commercial drinking water), or as a combination thereof. Accordingly, treating or remediating water contaminated with atrazine is of particular interest in the field of environmental science and technology focusing on treating or remediating contaminated or polluted water.

The following Examples 1-4 are based on catalytically treating water contaminated with atrazine (as an exemplary CONH type of halogenated organic herbicide water contaminant), according to homogeneous catalysis, via a batch mode, using different metalloporphyrin complex type electron transfer mediator (homogeneous) catalysts, and different types of bulk electron donors or reducing agents. Examples 1-4 clearly exemplify implementation of the hereinabove illustratively described present invention.

Materials and Experimental Methods

Water:

Distilled deionized filtered water, generated by a Milli-Q water purification system, was exclusively used throughout.

Atrazine—Water Contaminant:

Atrazine, 99%, was obtained from Agan Chemicals, Ashdod, Israel.

Atrazine Contaminated Water:

Stock solutions of water contaminated with atrazine at a concentration of 28 mg, 12 mg, or 2.8 mg, atrazine per liter water, corresponding to 28 ppm, 12 ppm, or 2.8 ppm, respectively, atrazine in the contaminated water, were prepared by dissolving the appropriate quantity of the atrazine in the distilled deionized filtered water. (at the conditions used, maximum solubility of atrazine in water is about 28 mg per liter (28 ppm)).

Electron Transfer Mediator (Homogeneous) Catalysts:

The (free base) porphyrins: tetramethylpyridilporphyrin [5,10,15,20-tetrakis(1-methyl-4-pyridinio)-porphine] [TMPyP]; tetrahydroxyphenylporphyrine [5,10,15,20-tetrakis(4-hydroxyphenyl)-21H,23H-porphine] [TP(OH)P]; and 4,4′,4″,4″′-(porphine-5,10,15,20-tetrayl)tetrakis(benzenesulfonic acid) [TBSP], were obtained from Aldrich.

The metalloporphyrin complexes: tetramethylpyridilporphyrin-Nickel [5,10,15,20-tetrakis(1-methyl-4-pyridinio)-porphine-Nickel] [TMPyP-Ni]; tetrahydroxyphenylporphyrine-Cobalt [5,10,15,20-tetrakis(4-hydroxyphenyl)-21H,23H-porphine-Cobalt] [TP(OH)P—Co]; tetramethylpyridilporphyrin-Cobalt [5,10,15,20-tetrakis(1-methyl-4-pyridinio)-porphine-cobalt] [TMPyP-Co]; and 4,4′,4″,4″′-(porphine-5,10,15,20-tetrayl)tetrakis(benzenesulfonic acid)-Cobalt [TBSP-Co], were synthesized from the respective [TMPyP], [TP(OH)P], and [TBSP], (free base) porphyrins and transition metal solutions using published methods and techniques [61, 100, 101].

An aqueous stock solution of the [TMPyP-Ni] metalloporphyrin complex, at a concentration of 2 mM, was prepared by dissolving the synthesized [TMPyP-Ni] metalloporphyrin complex in the distilled deionized filtered water at pH 5-9. This stock solution was used in Example 1 for providing the [TMPyP-Ni] metalloporphyrin complex electron transfer mediator (homogeneous) catalyst.

An aqueous stock solution of the [TP(OH)P—Co] metalloporphyrin complex, at a concentration of 2 mM, was prepared by dissolving the synthesized [TP(OH)P—Co] metalloporphyrin complex in the distilled deionized filtered water previously adjusted to pH greater than 7.5 by adding analytical grade sodium hydroxide [NaOH] solution. This stock solution was used in Example 2 for providing the [TP(OH)P—Co] metalloporphyrin complex electron transfer mediator (homogeneous) catalyst.

An aqueous stock solution of the [TMPyP-Co] metalloporphyrin complex, at a concentration of 2 mM, was prepared by dissolving the synthesized [TMPyP-Co] metalloporphyrin complex in the distilled deionized filtered water at pH 5-9. This stock solution was used in Example 3 for providing the [TMPyP-Co] metalloporphyrin complex electron transfer mediator (homogeneous) catalyst.

An aqueous stock solution of the [TBSP-Co] metalloporphyrin complex, at a concentration of 2 mM, was prepared by dissolving the synthesized [TBSP-Co] metalloporphyrin complex in the distilled deionized filtered water previously adjusted to pH greater than 7 by adding analytical grade sodium hydroxide [NaOH] solution. This stock solution was used in Example 4 for providing the [TBSP-Co] metalloporphyrin complex electron transfer mediator (homogeneous) catalyst.

Bulk Electron Donors or Reducing Agents:

Zero valent iron [Fe⁰], in a nano-sized particulate form, was synthesized using published methods and techniques [102]. Prior to use, the dry zero valent iron particles were stored in an anaerobic chamber (Coy Laboratory Products, MI, USA) containing an oxygen free atmosphere composed of a mixture of nitrogen [N₂] gas and hydrogen [H₂] gas, having a 95/5 molar or partial pressure ratio. The zero valent iron was used as the bulk electron donor or reducing agent in Example 1.

Titanium (III) citrate [Ti(OC(CH₂COOH)₂COOH], in aqueous solution form, was synthesized, using published methods and techniques [102, 96]. The prepared solution of 250 mM titanium (III) citrate in 660 mM tris buffer (pH 8.2) was aliquoted to vials, which were sealed and stored at −20° C. until use. The titanium (III) citrate was used as the bulk electron donor or reducing agent in Examples 2, 3, and 4.

Homogeneous Catalytic Batch Reactor (as an exemplary in-situ unit):

In Examples 1 and 2, 500 milliliter (0.5 liter) glass beakers were used at room temperature (between about 20° C. and about 25° C.) and atmospheric pressure. Contents of each glass beaker (batch reactor) were mixed by securing the glass beaker onto an orbital shaker (model TS-600, from MRC, Israel) having automatic (mixing) speed control.

In Examples 3 and 4, 40 milliliter (0.04 liter) glass vials (usually filled with about 25 milliliters of reaction solution), fitted with Teflon®-clear silicon sealing cups, were used at room temperature (between about 20° C. and about 25° C.) and atmospheric pressure. Contents of each glass vial (batch reactor) were mixed by securing the glass vial onto the orbital shaker. Multiple replicates of each glass vial (batch reactor) filled with reaction solution were prepared at the beginning of an experiment.

In each of Examples 1-4, the glass beaker or glass vial batch mode reaction systems were prepared under oxygen free atmosphere conditions, using the same anaerobic chamber described above.

Analytical Procedures:

GC and GC/MS were used for monitoring concentration over time, of atrazine, and of the ‘sole’ atrazine catalytic reductive dechlorination reaction product formed, N²,N⁴-diethyl-6-methyl-1,3,5-triazine-2,4-diamine, in the atrazine contaminated water, during the batch mode homogeneous catalytic reactions of Examples 1-4.

The GC was an HP 5890. The GC/MS was Varian, Saturn 2000. For both the GC and GC/MS, the GC column used was a J&W Scientific—DB5 capillary column, 30 meter length, 0.25 mm inner diameter, and 0.25 micron film layer thickness. For both the GC and GC/MS, the GC program was: 160° C. for 2 minutes; temperature ramp of 8° C. per minute to 205° C.; hold for 1 minute.

For the GC and GC/MS analytical procedures, acquiring and preparing samples from the glass beaker or glass vial (batch reactor), and preparing standard reference samples, were done using the same anaerobic chamber described above. Time dependent samples were acquired from each catalytic reaction ‘in-progress’, and from identical repetitions of each such progressing catalytic reaction.

In Examples 3 and 4, for each sampling point, the GC and GC/MS analytical procedures included opening (thereby, sacrificing) at least two glass vials (batch reactors), followed by extracting the organic phase from the aqueous reaction solution contained in each glass vial using 5 milliliters of methylene chloride (dichloromethane) [99.8%; Sigma-Aldrich] as extraction solvent. The extracted organic phase was then transferred to a gas chromatograph vial and analyzed for the presence of the atrazine contaminant or/and degradation product(s) thereof.

As a standard reference in the GC and GC/MS analytical procedures, the N²,N⁴-diethyl-6-methyl-1,3,5-triazine-2,4-diamine reaction product was synthesized as summarized hereinbelow:

The above synthesis corresponds to modification of a published method [103] used for synthesizing the 2,4-di-n-propylamino-6-methyl-s-triazine analog thereof.

Example 1 Catalytically Treating Water Contaminated with Atrazine According to Homogeneous Catalysis Via a Batch Mode [TMPyP-Ni] Electron Transfer Mediator Catalyst, Zero Valent Iron [Fe⁰] Bulk Electron Donor Experimental Procedure

Example 1 was performed at room temperature (between about 20° C. and about 25° C.) and atmospheric pressure.

A volume of 500 milliliter (0.5 liter) was taken from the stock solution of water contaminated with atrazine and added to the empty glass beaker (batch reactor), for providing an initial concentration of atrazine of 12 mg atrazine per liter contaminated water, or 12 ppm atrazine in the contaminated water.

Reducing conditions were not naturally prevalent in the atrazine contaminated water in the glass beaker (batch reactor) for effectively enabling the phenomena, mechanisms, and processes of the electron transfer mediated (homogeneous) catalytic reductive dehalogenation of the atrazine contaminant in the contaminated water. Thus, reducing conditions in the atrazine contaminated water were anthropogenically produced by exposing the atrazine contaminated water to zero valent iron particles as the bulk electron donor or reducing agent, immediately before exposing the atrazine contaminated water to the catalytically effective amount of the [TMPyP-Ni] metalloporphyrin complex electron transfer mediator (homogeneous catalyst).

For this, about 2 grams (on a ‘dry basis’) of the zero valent iron [Fe⁰] nano-sized particles were added to the atrazine contaminated water contained in the glass beaker (batch reactor), for providing a concentration of about 4 grams (0.071 mole) zero valent iron particles (bulk electron donor or reducing agent) per liter atrazine contaminated water.

Then, an appropriate volume was taken from the 2 mM [TMPyP-Ni] metalloporphyrin complex stock solution, and added to the 0.5 liter of atrazine contaminated water and zero valent iron particles contained in the glass beaker (batch reactor), for providing a concentration of about 0.014 mM [TMPyP-Ni] metalloporphyrin complex electron transfer mediator (homogeneous) catalyst in the atrazine contaminated water.

The contents, i.e., the atrazine contaminated water containing the zero valent iron particles as bulk electron donor or reducing agent and the [TMPyP-Ni] metalloporphyrin complex electron transfer mediator (homogeneous) catalyst, in the glass beaker (batch reactor), were continuously mixed by securing the glass beaker onto the orbital shaker set at a mixing speed of 150 rpm during the entire extent of time or duration of reaction.

GC and GC/MS analytical samples were periodically taken from the atrazine contaminated water of the batch mode homogeneous catalytic reductive dechlorination reaction, during which mixing of the contents of the glass beaker (batch reactor) was briefly, temporarily stopped, and then continued.

Experimental Results

The results obtained for Example 1 are presented in the following Table 1.

TABLE 1 Normalized concentration of atrazine measured as a function of time (hours) for the batch mode homogeneous catalytic reductive dechlorination reaction of atrazine in atrazine contaminated water, effected by the [TMPyP-Ni] metalloporphyrin complex electron transfer mediator (homogeneous) catalyst, and the zero valent iron particles as bulk electron donor or reducing agent, at room temperature and atmospheric pressure. Time Normalized atrazine (hours) concentration 1.25 1 24 0.18 48 0.06 72 0.04

The results presented in Table 1 show that after 24 hours, and 72 hours, the initial atrazine concentration in the atrazine contaminated water decreased by more than 80%, and by more than 95%, respectively.

From the results of the GC and GC/MS analyses of Example 1, the sole atrazine catalytic reductive dechlorination reaction product formed during the batch mode homogeneous catalytic reaction was identified as N²,N⁴-diethyl-6-methyl-1,3,5-triazine-2,4-diamine [equivalently named: 2,4-bis(ethylamine)-6-methyl-s-triazine, or methylated s-triazine]. Accordingly, the atrazine in the atrazine contaminated water underwent catalytic degradation, transformation, or conversion, as follows:

The atrazine catalytic reductive dechlorination reaction product, N²,N⁴-diethyl-6-methyl-1,3,5-triazine-2,4-diamine, is relatively hydrophobic, and is expected to be much less mobile and soluble in water compared to the parent compound, atrazine. Moreover, such a non-chlorinated organic compound is expected to be non-hazardous, or at least, less hazardous, and therefore, more environmentally friendly, than atrazine.

The atrazine degradation product, N²,N⁴-diethyl-6-methyl-1,3,5-triazine-2,4-diamine, was previously obtained as a minor one of three photolytic degradation products formed during ultraviolet photolysis of atrazine present on a soil surface [37, 38]. The methods and procedures taught therein for photolytically degrading atrazine are specifically limited to the atrazine being present on a soil surface, and are clearly significantly different than those of the present invention for catalytically treating water contaminated with atrazine as just one example of a halogenated organic herbicide type of halogenated organic compound.

Example 2 Catalytically Treating Water Contaminated with Atrazine According to Homogeneous Catalysis Via a Batch Mode [TP(OH)P—Co] Electron Transfer Mediator Catalyst, Titanium (III) Citrate Bulk Electron Donor Experimental Procedure

Example 2 was performed at room temperature (between about 20° C. and about 25° C.) and atmospheric pressure.

A volume of 500 milliliter (0.5 liter) was taken from the stock solution of water contaminated with atrazine and added to the empty glass beaker (batch reactor), for providing an initial concentration of atrazine of 12 mg atrazine per liter contaminated water, or 12 ppm atrazine in the contaminated water.

Reducing conditions were not naturally prevalent in the atrazine contaminated water in the glass beaker (batch reactor) for effectively enabling the phenomena, mechanisms, and processes of the electron transfer mediated (homogeneous) catalytic reductive dehalogenation of the atrazine contaminant in the contaminated water. Thus, reducing conditions in the atrazine contaminated water were anthropogenically produced by exposing the atrazine contaminated water to titanium (III) citrate [Ti(OC(CH₂COOH)₂COOH] as the bulk electron donor or reducing agent, immediately before exposing the atrazine contaminated water to the catalytically effective amount of the [TP(OH)P—Co] metalloporphyrin complex electron transfer mediator (homogeneous catalyst).

For this, a number of the (−20° C. stored) vials of the prepared solution of 250 mM titanium (III) citrate in 660 mM tris buffer (pH 8.2) were brought to room temperature. Then, a volume of about 36 milliliters was taken therefrom, and added to the 0.5 liter of atrazine contaminated water contained in the glass beaker (batch reactor), for providing a concentration of about 0.014 M titanium (III) citrate (bulk electron donor or reducing agent) in the atrazine contaminated water.

Then, an appropriate volume was taken from the 2 mM [TP(OH)P—Co] metalloporphyrin complex stock solution, and added to the 0.5 liter of atrazine contaminated water and titanium (III) citrate contained in the glass beaker (batch reactor), for providing a concentration of about 0.014 mM [TP(OH)P—Co] metalloporphyrin complex electron transfer mediator (homogeneous) catalyst in the atrazine contaminated water.

The contents, i.e., the atrazine contaminated water containing the titanium (III) citrate as bulk electron donor or reducing agent and the [TP(OH)P—Co] metalloporphyrin complex electron transfer mediator (homogeneous) catalyst, in the glass beaker (batch reactor), were continuously mixed by securing the glass beaker onto the orbital shaker set at a mixing speed of 150 rpm during the entire extent of time or duration of reaction.

GC and GC/MS analytical samples were periodically taken from the atrazine contaminated water of the batch mode homogeneous catalytic reductive dechlorination reaction, during which mixing of the contents of the glass beaker (batch reactor) was briefly, temporarily stopped, and then continued.

Experimental Results

The results obtained for Example 2 are presented in the following Table 2.

TABLE 2 Normalized concentration of atrazine measured as a function of time (hours) for the batch mode homogeneous catalytic reductive dechlorination reaction of atrazine in atrazine contaminated water, effected by the [TP(OH)P-Co] metalloporphyrin complex electron transfer mediator (homogeneous) catalyst, and the titanium (III) citrate as bulk electron donor or reducing agent, at room temperature and atmospheric pressure. Time Normalized atrazine (hours) concentration 0 1.000 1.25 0.268 2 0.100 4 0.056 6 0.029 8 0.024 10 0.014 12 0.011 48 0.000

The results presented in Table 2 show that already after 2 hours, the initial atrazine concentration in the atrazine contaminated water decreased by 90%. After 12 hours, and 48 hours, the initial atrazine concentration in the atrazine contaminated water decreased by about 99%, and by about 100% (i.e., completely), respectively.

From the results of the GC and GC/MS analyses of Example 2, the sole atrazine catalytic reductive dechlorination reaction product formed during the batch mode homogeneous catalytic reaction was identified as N²,N⁴-diethyl-6-methyl-1,3,5-triazine-2,4-diamine [2,4-bis(ethylamine)-6-methyl-s-triazine, or methylated s-triazine]. Apparently, in Example 2, involving a different metalloporphyrin complex electron transfer mediator (homogeneous) catalyst, and a different bulk electron donor or reducing agent, reacting under otherwise similar conditions, compared to those of Example 1, the atrazine in the atrazine contaminated water underwent catalytic degradation, transformation, or conversion, in the same or similar manner as that shown and discussed in Example 1, above.

Example 3 Catalytically Treating Water Contaminated with Atrazine According to Homogeneous Catalysis Via a Batch Mode [TMPyP-Co] Electron Transfer Mediator Catalyst, Titanium (III) Citrate Bulk Electron Donor Experimental Procedure

Example 3 was performed at room temperature (between about 20° C. and about 25° C.) and atmospheric pressure.

A volume of 25 milliliter (0.025 liter) was taken from the appropriate stock solution of water contaminated with atrazine and added to the empty 40 milliliter glass vial (batch reactor), for providing an initial concentration of atrazine of 28 mg atrazine per liter contaminated water, or 28 ppm atrazine in the contaminated water. This procedure was repeated, for preparing at least two glass vials (batch reactors) for each sampling point.

Reducing conditions were not naturally prevalent in the atrazine contaminated water in the glass vials (batch reactors) for effectively enabling the phenomena, mechanisms, and processes of the electron transfer mediated (homogeneous) catalytic reductive dehalogenation of the atrazine contaminant in the contaminated water. Thus, reducing conditions in the atrazine contaminated water were anthropogenically produced by exposing the atrazine contaminated water to titanium (III) citrate [Ti(OC(CH₂COOH)₂COOH] as the bulk electron donor or reducing agent, immediately before exposing the atrazine contaminated water to the catalytically effective amount of the [TMPyP-Co] metalloporphyrin complex electron transfer mediator (homogeneous catalyst).

For this, a number of the (−20° C. stored) vials of the prepared solution of 250 mM titanium (III) citrate in 660 mM tris buffer (pH 8.2) were brought to room temperature. Then, a volume of 0.75 milliliter was taken and added to the atrazine contaminated water contained in each glass vial (batch reactor), for providing a concentration of about 0.0073 M titanium (III) citrate (bulk electron donor or reducing agent) in the atrazine contaminated water. The pH of the solution was then adjusted to the desired value (e.g., 8.5) by adding small amounts of NaOH concentrated solution to each glass vial (batch reactor).

Then, an appropriate volume was taken from the 2 mM [TMPyP-Co] metalloporphyrin complex stock solution, and added to each glass vial (batch reactor) containing atrazine contaminated water and titanium (III) citrate, for providing a concentration of about 0.013 mM [TMPyP-Co] metalloporphyrin complex electron transfer mediator (homogeneous) catalyst in the atrazine contaminated water. At this point, the glass vials were sealed, and transferred to the orbital shaker.

The contents, i.e., the atrazine contaminated water containing the titanium (III) citrate as bulk electron donor or reducing agent and the [TMPyP-Co] metalloporphyrin complex electron transfer mediator (homogeneous) catalyst, in each glass vial (batch reactor), were continuously mixed by securing each glass vial onto the orbital shaker set at a mixing speed of 150 rpm during the entire extent of time or duration of reaction.

For each sampling point, GC or GC/MS analytical samples were periodically prepared from each of at least two glass vials containing the atrazine contaminated water of the batch mode homogeneous catalytic reductive dechlorination reaction. Mixing of the contents of the glass vials (batch reactors) was briefly, temporarily stopped, only to remove the sampled vials, and then continued. The organic phase was extracted from the aqueous reaction solution contained in each glass vial using 5 milliliters of methylene chloride (dichloromethane) as extraction solvent. The extracted organic phase was then analyzed for the presence of the atrazine contaminant or/and degradation product(s) thereof.

Experimental Results

The results obtained for Example 3 are presented in the following Table 3.

TABLE 3 Normalized concentration of atrazine measured as a function of time (hours) for the batch mode homogeneous catalytic reductive dechlorination reaction of atrazine in atrazine contaminated water, effected by the [TMPyP-Co] metalloporphyrin complex electron transfer mediator (homogeneous) catalyst, and the titanium (III) citrate as bulk electron donor or reducing agent, at room temperature and atmospheric pressure. Time Normalized atrazine (hours) concentration 0.0 1.000 0.25 0.36 0.5 0.14 1.0 0.07 2.0 0.05 3.0 0.00 4.0 0.00

The results presented in Table 3 show that already after 0.5 hour, the initial atrazine concentration in the atrazine contaminated water decreased by about 85%. After 2.0 hours, and 3.0 hours, the initial atrazine concentration in the atrazine contaminated water decreased by about 95%, and by about 100% (i.e., completely), respectively.

From the results of the GC and GC/MS analyses of Example 3, the sole atrazine catalytic reductive dechlorination reaction product formed during the batch mode homogeneous catalytic reaction was identified as N²,N⁴-diethyl-6-methyl-1,3,5-triazine-2,4-diamine [2,4-bis(ethylamine)-6-methyl-s-triazine, or methylated s-triazine]. Apparently, in Example 3, the atrazine in the atrazine contaminated water underwent catalytic degradation, transformation, or conversion, in the same or similar manner as that shown and discussed in Examples 1 and 2, above.

Example 4 Catalytically Treating Water Contaminated with Atrazine According to Homogeneous Catalysis Via a Batch Mode [TBSP-Co] Electron Transfer Mediator Catalyst, Titanium (III) Citrate Bulk Electron Donor Experimental Procedure

Example 4 was performed at room temperature (between about 20° C. and about 25° C.) and atmospheric pressure.

A volume of 25 milliliter (0.025 liter) was taken from the appropriate stock solution of water contaminated with atrazine and added to the empty 40 milliliter glass vial (batch reactor), for providing an initial concentration of atrazine of 12 mg atrazine per liter contaminated water, or 12 ppm atrazine in the contaminated water. This procedure was repeated, for preparing at least two glass vials (batch reactors) for each sampling point.

Reducing conditions were not naturally prevalent in the atrazine contaminated water in the glass vials (batch reactors) for effectively enabling the phenomena, mechanisms, and processes of the electron transfer mediated (homogeneous) catalytic reductive dehalogenation of the atrazine contaminant in the contaminated water. Thus, reducing conditions in the atrazine contaminated water were anthropogenically produced by exposing the atrazine contaminated water to titanium (III) citrate [Ti(OC(CH₂COOH)₂COOH] as the bulk electron donor or reducing agent, immediately before exposing the atrazine contaminated water to the catalytically effective amount of the [TBSP-Co] metalloporphyrin complex electron transfer mediator (homogeneous catalyst).

For this, a number of the (−20° C. stored) vials of the prepared solution of 250 mM titanium (III) citrate in 660 mM tris buffer (pH 8.2) were brought to room temperature. Then, a volume of 0.75 milliliter was taken and added to the atrazine contaminated water contained in each glass vial (batch reactor), for providing a concentration of about 0.0073 M titanium (III) citrate (bulk electron donor or reducing agent) in the atrazine contaminated water. The pH of the solution was then adjusted to the desired value (e.g., 9.5) by adding small amounts of NaOH concentrated solution to each glass vial (batch reactor).

Then, an appropriate volume was taken from the 2 mM [TBSP-Co] metalloporphyrin complex stock solution, and added to each glass vial (batch reactor) containing atrazine contaminated water and titanium (III) citrate, for providing a concentration of about 0.056 mM [TBSP-Co] metalloporphyrin complex electron transfer mediator (homogeneous) catalyst in the atrazine contaminated water. At this point, the glass vials were sealed, and transferred to the orbital shaker.

The contents, i.e., the atrazine contaminated water containing the titanium (III) citrate as bulk electron donor or reducing agent and the [TBSP-Co] metalloporphyrin complex electron transfer mediator (homogeneous) catalyst, in each glass vial (batch reactor), were continuously mixed by securing each glass vial onto the orbital shaker set at a mixing speed of 150 rpm during the entire extent of time or duration of reaction.

For each sampling point, GC or GC/MS analytical samples were periodically prepared from each of at least two glass vials containing the atrazine contaminated water of the batch mode homogeneous catalytic reductive dechlorination reaction. Mixing of the contents of the glass vials (batch reactors) was briefly, temporarily stopped, only to remove the sampled vials, and then continued. The organic phase was extracted from the aqueous reaction solution contained in each glass vial using 5 milliliters of methylene chloride (dichloromethane) as extraction solvent. The extracted organic phase was then analyzed for the presence of the atrazine contaminant or/and degradation product(s) thereof.

Experimental Results

The results obtained for Example 4, showed that for the batch mode homogeneous catalytic reductive dechlorination reaction of atrazine in atrazine contaminated water, effected by the [TBSP-Co] metalloporphyrin complex electron transfer mediator (homogeneous) catalyst, and the titanium (III) citrate as bulk electron donor or reducing agent, at room temperature and atmospheric pressure, already after 22 hours, the initial atrazine concentration in the atrazine contaminated water decreased by about 83%.

From the results of the GC and GC/MS analyses of Example 4, the sole atrazine catalytic reductive dechlorination reaction product formed during the batch mode homogeneous catalytic reaction was identified as N²,N⁴-diethyl-6-methyl-1,3,5-triazine-2,4-diamine [2,4-bis(ethylamine)-6-methyl-s-triazine, or methylated s-triazine]. Apparently, in Example 4, the atrazine in the atrazine contaminated water underwent catalytic degradation, transformation, or conversion, in the same or similar manner as that shown and discussed in Examples 1, 2, and 3, above.

From the results of the above Examples 1-4, occurrence of the same overall reaction transformations, i.e., atrazine to N²,N⁴-diethyl-6-methyl-1,3,5-triazine-2,4-diamine [2,4-bis(ethylamine)-6-methyl-s-triazine, or methylated s-triazine], involving different metalloporphyrin complex electron transfer mediator (homogeneous) catalysts, or/and different bulk electron donor or reducing agents, reacting under otherwise similar conditions, strongly suggests that the overall reaction is typical and unique for catalytically treating water contaminated with atrazine.

Moreover, since only a sole atrazine catalytic reductive dechlorination reaction product, i.e., N²,N⁴-diethyl-6-methyl-1,3,5-triazine-2,4-diamine [2,4-bis(ethylamine)-6-methyl-s-triazine, or methylated s-triazine], was formed under these conditions (via different metalloporphyrin complex electron transfer mediator (homogeneous) catalysts, or/and different bulk electron donor or reducing agents), demonstrates a very high selectivity, yielding no other or/and additional harmful or interfering reaction products that may undesirably interfere with the reaction mechanism and associated pathway, or/and with the ecological system or/and with organisms thereof.

Mass Balance for the Reaction Systems of Examples 1-4:

For studying the mass balance for the reaction systems of above Examples 1-4, the catalytic degradation, transformation, or conversion, of the atrazine in the atrazine contaminated water was examined at three different concentrations, i.e., 28 mg, 12 mg, or 2.8 mg, atrazine per liter water, corresponding to 28 ppm, 12 ppm, or 2.8 ppm, respectively, atrazine in the contaminated water. Since the sole atrazine catalytic reductive dechlorination reaction product, N²,N⁴-diethyl-6-methyl-1,3,5-triazine-2,4-diamine [2,4-bis(ethylamine)-6-methyl-s-triazine, or methylated s-triazine], which was formed during the batch mode homogeneous catalytic reaction, was assumed to have lower solubility than the parent atrazine (based on theoretical considerations, although both species have relatively low solubility in water), it was observed that at the higher concentrations, e.g., 28 ppm atrazine in the contaminated water, some mass was lost due to partial precipitation of the methylated s-triazine reaction product, which was not recovered for analysis. The mass balance showed a trend of higher losses for higher atrazine concentration, and at the lowest initial concentration, i.e., 2.8 ppm atrazine in the contaminated water, a complete mass balance was found. This indicated that the gap between complete mass balance and measured results is probably due to a concentration effect.

The preceding described difference in solubility of the parent atrazine herbicide compared to the methylated s-triazine reaction product is beneficial from an environmental point of view, since lower dissolution (i.e., lower solubility) implies even more limited transport or mobility of the methylated s-triazine reaction product within or throughout groundwater (e.g., sub-surface water regions, reservoirs, or aquifers). This behavior, when combined with higher theoretical product degradation, and high reaction selectivity, provides a relatively clean and efficient process for treating or remediating water contaminated or polluted with halogenated organic compounds, such as atrazine.

The present invention, as illustratively described and exemplified hereinabove, has several beneficial and advantageous aspects, characteristics, and features, which are based on or/and a consequence of, the above illustratively described main aspects of novelty and inventiveness.

The present invention is applicable for treating or remediating water contaminated with a relatively wide concentration range of halogenated organic herbicides.

The present invention is applicable for (in-situ or ex-situ) homogeneously or heterogeneously catalytically treating water contaminated with halogenated organic herbicide compounds, where the contaminated water is in a variety of different forms, such as groundwater (e.g., sub-surface water regions, reservoirs, or aquifers), surface water (e.g., rivers, lakes, ponds, pools, or surface water reservoirs), above surface water (e.g., above surface water reservoirs, or above surface sources or supplies of residential or commercial drinking water), or as a combination thereof. Moreover, the present invention is commercially applicable for treating relatively large (commercial) quantities or volumes of such forms of contaminated water.

The present invention involves a relatively robust electron transfer mediated dehalogenation type of redox (reduction-oxidation) (homogeneous or heterogeneous) catalytic chemical reaction process which takes place within a wide range of environmental conditions, is minimally influenced by significant changes in reaction parameters of pH and temperature, and is independent of nutrient availability. These aspects are in strong contrast to the various limitations associated with biological techniques used for treating or remediating water contaminated or polluted with halogenated organic herbicides.

A wide variety of different types of electron transfer mediators can be used for implementing the present invention. Moreover, one or more of the electron transfer mediators can be immobilized on or/and inside of a (particulate or/and non-particulate) solid support or matrix material, which is then dispersed throughout the contaminated water.

Different types of naturally existing or/and man-made reducing conditions, involving various bulk electron donors or reducing agents, can be used for implementing the present invention.

The present invention can be integrated with zero valent metal (ZVM) types of reductive dehalogenation techniques for treating or remediating water contaminated or polluted with halogenated organic herbicides.

The electron transfer mediated dehalogenation redox catalytic chemical process is relatively simple, involving one or more electron transfer mediators reacting under reducing (anaerobic or anoxic) conditions for transforming, converting, or degrading, the halogenated organic herbicide contaminants to non-hazardous or/and less hazardous compounds.

The electron transfer mediated dehalogenation redox catalytic chemical process is relatively fast. Complete transformation, conversion, or degradation, of the halogenated organic herbicide contaminants to non-hazardous or/and less hazardous compounds and typically requires only hours or days following exposure of the contaminated water to the electron transfer mediator(s).

Following heterogeneous catalytic treatment of the contaminated water, an electron transfer mediator solid supported or matrixed configuration type heterogeneous catalyst can be removed from a given in-situ or ex-situ unit used for treating the contaminated water, and be recycled for again treating the contaminated water. Such recycling of the catalyst translates to a relatively cost effective method for treating water contaminated with halogenated organic herbicides.

Based upon the above indicated aspects of novelty and inventiveness, and, beneficial and advantageous aspects, characteristics, and features, the present invention successfully addresses shortcomings and limitations, and widens the scope, of presently known techniques in the field of environmental science and technology focusing on treating or remediating water contaminated or polluted with halogenated organic herbicide compounds, where the contaminated or polluted water is a form of groundwater, surface water, above surface water, or as a combination thereof. Moreover, commercial application of the present invention could provide a legal and environmentally friendly way or means to the field of agriculture for continuing use of proven or potentially hazardous, but highly effective, halogenated organic herbicides, in general, and chlorinated organonitrogen herbicides (CONHs), in particular.

It is appreciated that certain aspects and characteristics of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various aspects and characteristics of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.

All publications, patents and patent applications mentioned in this specification are herein incorporated in their entirety by reference into the specification, to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated herein by reference. In addition, citation or identification of any reference in this application shall not be construed as an admission that such reference is available as prior art to the present invention.

While the invention has been described in conjunction with specific embodiments and examples thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims.

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1. A method of catalytically treating water contaminated with halogenated organic compounds, wherein the halogenated organic compounds are selected from the group consisting of chlorotriazine herbicides, chloroacetanilide herbicides, halogenated aliphatic herbicides, halogen containing analogs thereof, halogen containing derivatives thereof, and combinations thereof, the method comprising exposing the contaminated water to a catalytically effective amount of at least one electron transfer mediator under reducing conditions, to thereby decrease concentration of at least one of the halogenated organic compounds in the contaminated water.
 2. (canceled)
 3. The method of claim 1, wherein said chlorotriazine herbicides have the general chemical structure:

wherein R₁-R₄ are each independently selected from the group consisting of a hydrogen atom and an organic substituent.
 4. The method of claim 3, wherein said organic substituent is selected from the group consisting of alkyl, cycloalkyl, cyanoalkyl, alkenyl, alkynyl, carboxylic acid, ether, alkoxy, heteroaryl, aryl, and heteroalicyclic.
 5. The method of claim 1, wherein said chlorotriazine herbicides are selected from the group consisting of atrazine [C₈H₁₄ClN₅], chlorazine [C₁₁H₂₀ClN₅], cyanazine [C₉H₁₃ClN₆], cyprazine [C₉H₁₄ClN₅], eglinazine [C₇H₁₀ClN₅O₂], ipazine [C₁₀H₁₈ClN₅], mesoprazine [C₁₀H₁₈ClN₅O], procyazine [C₁₀H₁₃ClN₆], proglinazine [C₈H₁₂ClN₅O₂], propazine [C₉H₁₆ClN₅], sebuthylazine [C₉H₁₆ClN₅], simazine [C₇H₁₂ClN₅], terbuthylazine [C₉H₁₆ClN₅], and trietazine [C₉H₁₆ClN₅].
 6. The method of claim 1, wherein said chloroacetanilide herbicides have the general chemical structure:

wherein R₁-R₄ are each independently selected from the group consisting of a hydrogen atom and an organic substituent.
 7. The method of claim 6, wherein said organic substituent is selected from the group consisting of alkyl, cycloalkyl, cyanoalkyl, alkenyl, alkynyl, carboxylic acid, ether, alkoxy, heteroaryl, aryl, and heteroalicyclic.
 8. The method of claim 1, wherein said chloroacetanilide herbicides are selected from the group consisting of acetochlor [C₁₄H₂₀ClNO₂], alachlor [C₁₄H₂₀ClNO₂], butachlor [C₁₇H₂₆ClNO₂], metazachlor [C₁₄H₁₆ClN₃O], metolachlor [C₁₅H₂₂ClNO₂], S-metolachlor [Cl₅H₂₂ClNO₂], pretilachlor [C₁₇H₂₆ClNO₂], propachlor [C₁₁H₁₄ClNO], xylachlor [C₁₃H₁₈ClNO], butenachlor [C₁₇H₂₄ClNO₂], delachlor [Cl₅H₂₂ClNO₂], diethatyl [Cl₄H₁₈CNO₃], dimethachlor [C₁₃H₁₈ClNO₂], propisochlor [C₁₅H₂₂ClNO₂], prynachlor [C₁₂H₁₂ClNO], terbuchlor [C₁₈H₂₈ClNO₂], and thenylchlor [C₁₆H₁₈ClNO₂S].
 9. The method of claim 1, wherein said halogenated aliphatic herbicides have the general chemical structure: A-(C—R′—R″)_(n)—B wherein: n ranges from 1 to 4; and A, B, R′, and R″ are each independently selected from the group consisting of a hydrogen atom and an organic substituent, whereas at least one of A, B, R′, and R″ is a halogen atom.
 10. The method of claim 9, wherein said organic substituent is selected from the group consisting of alkyl, cycloalkyl, cyanoalkyl, alkenyl, alkynyl, carboxylic acid, ether, alkoxy, heteroaryl, aryl, and heteroalicyclic.
 11. The method of claim 1, wherein said halogenated aliphatic herbicides are selected from the group consisting of alorac [C₅HCl₅O₃], chloropon [C₃H₃Cl₃O₂], dalapon [C₃H₄Cl₂O₂], flupropanate [C₃H₂F₄O₂], TCA (trichloroacetic acid) [C₂HCl₃O₂], hexachloroacetone [C₃Cl₆O], iodomethane [CH₃I], methyl bromide [CH₃Br], monochloroacetic acid [C₂H₃ClO₂], and SMA (sodium chloroacetate) [C₂H₂ClNaO₂].
 12. (canceled)
 13. The method of claim 1, wherein said at least one electron transfer mediator is a porphyrinogenic organometallic complex.
 14. The method of claim 13, wherein said porphyrinogenic organometallic complex is selected from the group consisting of a metalloporphyrin complex, a metallocorrin complex, a metallochlorin complex, and any combination thereof.
 15. The method of claim 14, wherein said metalloporphyrin complex is composed of a transition metal complexed to a (initially free base) porphyrin selected from the group consisting of: tetramethylpyridilporphyrin [5,10,15,20-tetrakis(1-methyl-4-pyridinio)-porphine] [TMPyP]; tetrahydroxyphenylporphyrine [5,10,15,20-tetrakis(4-hydroxyphenyl)-21H,23H-porphine] [TP(OH)P]; tetraphenylporphyrin [5,10,15,20-tetraphenyl-21H,23H-porphine] [TPP]; and 4,4′,4″,4″′-(porphine-5,10,15,20-tetrayl)tetrakis(benzenesulfonic acid) [TBSP].
 16. (canceled)
 17. The method of claim 14, wherein said metalloporphyrin complex is selected from the group consisting of tetramethylpyridilporphyrin-Nickel [5,10,15,20-tetrakis(1-methyl-4-pyridinio)-porphine-Nickel] [TMPyP-Ni]; tetrahydroxyphenylporphyrine-Cobalt [5,10,15,20-tetrakis(4-hydroxyphenyl)-21H,23H-porphine-Cobalt] [TP(OH)P—Co]; tetramethylpyridilporphyrin-Cobalt [5,10,15,20-tetrakis(1-methyl-4-pyridinio)-porphine-Cobalt] [TMPyP-Co]; 4,4′,4″,4″′-(porphine-5,10,15,20-tetrayl)tetrakis(benzenesulfonic acid)-Cobalt [TBSP-Co]; and a combination thereof.
 18. The method of claim 14, wherein said metalloporphyrin complex is selected from the group consisting of a chlorophyll and a heme.
 19. The method of claim 14, wherein a said metallocorrin complex is vitamin B₁₂ [corrin ligand (porphyrin analog) complexed to a cobalt (III) ion].
 20. The method of claim 1, wherein said exposing is effected according to homogeneous catalysis, heterogeneous catalysis, or a combination thereof.
 21. The method of claim 20, wherein according to said heterogeneous catalysis, said at least one electron transfer mediator is supported, matrixed, intercalated, incorporated, or/and trapped, and generally immobile, on or/and inside of a solid support or matrix material which subsequently becomes dispersed throughout the contaminated water.
 22. (canceled)
 23. The method of claim 20, wherein according to said heterogeneous catalysis, said at least one electron transfer mediator is part of an electron transfer mediator solid supported or matrixed configuration being a diatomite/zero valent metal (ZVM)/electron transfer mediator composite type of heterogeneous catalyst.
 24. The method of claim 1, wherein said catalytically effective amount of said at least one electron transfer mediator to which the contaminated water is exposed has a molar concentration in a range of between about 10⁻⁷ and about 10⁻³ mole electron transfer mediator per liter contaminated water. 25-26. (canceled)
 27. The method of claim 1, wherein said catalytically effective amount of said at least one electron transfer mediator to which the contaminated water is exposed, in terms of a mass (weight) ratio of said at least one electron transfer mediator and at least one of the halogenated organic compounds in the contaminated water, is in a range of between about 1:1000 and about 1000:1. 28-29. (canceled)
 30. The method of claim 1, wherein said exposing is performed according to homogeneous catalysis, via a batch mode or a flow mode, for forming a homogeneous catalytic reaction system of either said mode. 31-32. (canceled)
 33. The method of claim 1, wherein said exposing is performed according to heterogeneous catalysis, via a batch mode or a flow mode, for forming a heterogeneous catalytic reaction system of either said mode.
 34. (canceled)
 35. The method of claim 1, wherein said reducing conditions naturally exist, or/and are anthropogenically produced, in the contaminated water.
 36. The method of claim 35, wherein said anthropogenically producing said reducing conditions is performed by exposing the contaminated water to at least one bulk electron donor or reducing agent.
 37. The method of claim 35, wherein said anthropogenically producing said reducing conditions is performed by using an electron transfer mediator solid supported or matrixed configuration type of heterogeneous catalyst that includes at least one bulk electron donor or reducing agent.
 38. The method of claim 36, wherein said at least one bulk electron donor or reducing agent comprises an elemental metal (a zero valent metal).
 39. (canceled)
 40. The method of claim 36, wherein said at least one bulk electron donor or reducing agent is selected from the group consisting of titanium (III) citrate [Ti(OC(CH₂COOH)₂COOH], potassium borohydride [KBH₄], sodium borohydride [NaBH₄], lithium hydride [LiH], potassium hydride [KaH], sodium hydride [NaH], borotrihydride [BH₃], aluminum trihydride [AlH₃], hydrazine [H₂NNH₂], triphenylphosphate [PPh₃], sodium dithionite (sodium hydrosulfite) [Na₂S₂O₄], and any combination thereof.
 41. The method of claim 36, wherein said at least one bulk electron donor or reducing agent has a molar concentration in a range of between about 10⁻⁴ and about 1.0 mole bulk electron donor or reducing agent per liter contaminated water. 42-43. (canceled)
 44. The method of claim 1, wherein said exposing is performed by using a system which includes said at least one electron transfer mediator, and at least one unit for containing said catalytically effective amount of said at least one electron transfer mediator.
 45. The method of claim 44, wherein said at least one unit includes an in-situ unit, said in-situ unit is essentially physically situated or located, and operative, at or within actual site, place, or location, of the contaminated water, during catalytically treating the contaminated water. 46-48. (canceled)
 49. The method of claim 44, wherein said at least one unit includes an ex-situ unit, said ex-situ unit is essentially physically situated or located, and operative, out of or away from actual site, place, or location, of the contaminated water, during catalytically treating the contaminated water.
 50. (canceled)
 51. A system for catalytically treating water contaminated with halogenated organic compounds, wherein the halogenated organic compounds are selected from the group consisting of chlorotriazine herbicides, chloroacetanilide herbicides, halogenated aliphatic herbicides, halogen containing analogs thereof, halogen containing derivatives thereof, and combinations thereof, the system comprising: (a) at least one electron transfer mediator; and (b) at least one unit for containing a catalytically effective amount of said at least one electron transfer mediator, for exposing the contaminated water to said at least one electron transfer mediator under reducing conditions.
 52. (canceled)
 53. The system of claim 51, wherein said chlorotriazine herbicides have the general chemical structure:

wherein R₁-R₄ are each independently selected from the group consisting of a hydrogen atom and an organic substituent.
 54. The system of claim 53, wherein said organic substituent is selected from the group consisting of alkyl, cycloalkyl, cyanoalkyl, alkenyl, alkynyl, carboxylic acid, ether, alkoxy, heteroaryl, aryl, and heteroalicyclic.
 55. The system of claim 51, wherein said chlorotriazine herbicides are selected from the group consisting of atrazine [C₈H₁₄ClN₅], chlorazine [C₁₁H₂₀ClN₅], cyanazine [C₉H₁₃ClN₆], cyprazine [C₉H₁₄ClN₅], eglinazine [C₇H₁₀ClN₅O₂], ipazine [C₁₀H₁₈ClN₅], mesoprazine [C₁₀H₁₈ClN₅O], procyazine [C₁₀H₁₃ClN₆], proglinazine [C₈H₁₂ClN₅O₂], propazine [C₉H₁₆ClN₅], sebuthylazine [C₉H₁₆ClN₅], simazine [C₇H₁₂ClN₅], terbuthylazine [C₉H₁₆ClN₅], and trietazine [C₉H₁₆ClN₅].
 56. The system of claim 51, wherein said chloroacetanilide herbicides have the general chemical structure:

wherein R₁-R₄ are each independently selected from the group consisting of a hydrogen atom and an organic substituent.
 57. The system of claim 56, wherein said organic substituent is selected from the group consisting of alkyl, cycloalkyl, cyanoalkyl, alkenyl, alkynyl, carboxylic acid, ether, alkoxy, heteroaryl, aryl, and heteroalicyclic.
 58. The system of claim 51, wherein said chloroacetanilide herbicides are selected from the group consisting of acetochlor [C₁₄H₂₀ClNO₂], alachlor [C₁₄H₂₀ClNO₂], butachlor [C₁₇H₂₆ClNO₂], metazachlor [C₁₄H₁₆ClN₃O], metolachlor [C₁₅H₂₂ClNO₂], S-metolachlor [C₁₅H₂₂ClNO₂], pretilachlor [C₁₇H₂₆ClNO₂], propachlor [C₁₁H₁₄ClNO], xylachlor [C₁₃H₁₈ClNO], butenachlor [C₁₇H₂₄ClNO₂], delachlor [C₁₅H₂₂ClNO₂], diethatyl [C₁₄H₁₈ClNO₃], dimethachlor [C₁₃H₁₈ClNO₂], propisochlor [C₅H₂₂ClNO₂], prynachlor [C₁₂H₁₂ClNO], terbuchlor [C₁₈H₂₈ClNO₂], and thenylchlor [C₁₆H₁₈ClNO₂S].
 59. The system of claim 51, wherein said halogenated aliphatic herbicides have the general chemical structure: A-C—R′—R″)_(n)—B wherein: n ranges from 1 to 4; and A, B, R′, and R″ are each independently selected from the group consisting of a hydrogen atom and an organic substituent, whereas at least one of A, B, R′, and R″ is a halogen atom.
 60. The system of claim 59, wherein said organic substituent is selected from the group consisting of alkyl, cycloalkyl, cyanoalkyl, alkenyl, alkynyl, carboxylic acid, ether, alkoxy, heteroaryl, aryl, and heteroalicyclic.
 61. The system of claim 51, wherein said halogenated aliphatic herbicides are selected from the group consisting of alorac [C₅HCl₅O₃], chloropon [C₃H₃Cl₃O₂], dalapon [C₃H₄Cl₂O₂], flupropanate [C₃H₂F₄O₂], TCA (trichloroacetic acid) [C₂HCl₃O₂], hexachloroacetone [C₃Cl₆O], iodomethane [CH₃I], methyl bromide [CH₃Br], monochloroacetic acid [C₂H₃ClO₂], and SMA (sodium chloroacetate) [C₂H₂ClNaO₂].
 62. (canceled)
 63. The system of claim 51, wherein said at least one electron transfer mediator is a porphyrinogenic organometallic complex.
 64. The system of claim 63, wherein said porphyrinogenic organometallic complex is selected from the group consisting of a metalloporphyrin complex, a metallocorrin complex, a metallochlorin complex, and any combination thereof.
 65. The system of claim 64, wherein said metalloporphyrin complex is composed of a transition metal complexed to a (initially free base) porphyrin selected from the group consisting of: tetramethylpyridilporphyrin [5,10,15,20-tetrakis(1-methyl-4-pyridinio)-porphine] [TMPyP]; tetrahydroxyphenylporphyrine [5,10,15,20-tetrakis(4-hydroxyphenyl)-21H,23H-porphine] [TP(OH)P]; tetraphenylporphyrin [5,10,15,20-tetraphenyl-21H,23H-porphine] [TPP]; and 4,4′,4″,4″′-(porphine-5,10,15,20-tetrayl)tetrakis(benzenesulfonic acid) [TBSP].
 66. (canceled)
 67. The system of claim 64, wherein said metalloporphyrin complex is selected from the group consisting of tetramethylpyridilporphyrin-Nickel [5,10,15,20-tetrakis(1-methyl-4-pyridinio)-porphine-Nickel] [TMPyP-Ni]; tetrahydroxyphenylporphyrine-Cobalt [5,10,15,20-tetrakis(4-hydroxyphenyl)-21H,23H-porphine-Cobalt] [TP(OH)P—Co]; tetramethylpyridilporphyrin-Cobalt [5,10,15,20-tetrakis(1-methyl-4-pyridinio)-porphine-Cobalt] [TMPyP-Co]; 4,4′,4″,4″′-(porphine-5,10,15,20-tetrayl)tetrakis(benzenesulfonic acid-Cobalt [TBSP-Co]; and a combination thereof.
 68. The system of claim 64, wherein said metalloporphyrin complex is selected from the group consisting of a chlorophyll and a heme.
 69. The system of claim 64, wherein a said metallocorrin complex is vitamin B₁₂ [corrin ligand (porphyrin analog) complexed to a cobalt (III) ion].
 70. The system of claim 51, wherein said exposing is effected according to homogeneous catalysis, heterogeneous catalysis, or a combination thereof.
 71. The system of claim 70, wherein according to said heterogeneous catalysis, said at least one electron transfer mediator is supported, matrixed, intercalated, incorporated, or/and trapped, and generally immobile, on or/and inside of a solid support or matrix material which subsequently becomes dispersed throughout the contaminated water.
 72. (canceled)
 73. The system of claim 70, wherein according to said heterogeneous catalysis, said at least one electron transfer mediator is part of an electron transfer mediator solid supported or matrixed configuration being a diatomite/zero valent metal (ZVM)/electron transfer mediator composite type of heterogeneous catalyst.
 74. The system of claim 51, wherein said catalytically effective amount of said at least one electron transfer mediator to which the contaminated water is exposed has a molar concentration in a range of between about 10⁻⁷ and about 10⁻³ mole electron transfer mediator per liter contaminated water. 75-76. (canceled)
 77. The system of claim 51, wherein said catalytically effective amount of said at least one electron transfer mediator to which the contaminated water is exposed, in terms of a mass (weight) ratio of said at least one electron transfer mediator and at least one of the halogenated organic compounds in the contaminated water, is in a range of between about 1:1000 and about 1000:1. 78-79. (canceled)
 80. The system of claim 51, wherein said exposing is performed according to homogeneous catalysis, via a batch mode or a flow mode, for forming a homogeneous catalytic reaction system of either said mode. 81-82. (canceled)
 83. The system of claim 51, wherein said exposing is performed according to heterogeneous catalysis, via a batch mode or a flow mode, for forming a heterogeneous catalytic reaction system of either said mode.
 84. (canceled)
 85. The system of claim 51, wherein said reducing conditions naturally exist, or/and are anthropogenically produced, in the contaminated water.
 86. The system of claim 85, wherein said anthropogenically producing said reducing conditions is performed by exposing the contaminated water to at least one bulk electron donor or reducing agent.
 87. The system of claim 85, wherein said anthropogenically producing said reducing conditions is performed by using an electron transfer mediator solid supported or matrixed configuration type of heterogeneous catalyst that includes at least one bulk electron donor or reducing agent.
 88. The system of claim 86, wherein said at least one bulk electron donor or reducing agent comprises an elemental metal (a zero valent metal).
 89. (canceled)
 90. The system of claim 86, wherein said at least one bulk electron donor or reducing agent is selected from the group consisting of titanium (III) citrate [Ti(OC(CH₂COOH)₂COOH], potassium borohydride [KBH₄], sodium borohydride [NaBH₄], lithium hydride [LiH], potassium hydride [KaH], sodium hydride [NaH], borotrihydride [BH₃], aluminum trihydride [AlH₃], hydrazine [H₂NNH₂], triphenylphosphate [PPh₃], sodium dithionite (sodium hydrosulfite) [Na₂S₂O₄], and any combination thereof.
 91. The system of claim 86, wherein said at least one bulk electron donor or reducing agent has a molar concentration in a range of between about 10⁻⁴ and about 1.0 mole bulk electron donor or reducing agent per liter contaminated water. 92-93. (canceled)
 94. The system of claim 51, wherein said at least one unit includes an in-situ unit, said in-situ unit is essentially physically situated or located, and operative, at or within actual site, place, or location, of the contaminated water, during catalytically treating the contaminated water. 95-97. (canceled)
 98. The system of claim 51, wherein said at least one unit includes an ex-situ unit, said ex-situ unit is essentially physically situated or located, and operative, out of or away from actual site, place, or location, of the contaminated water, during catalytically treating the contaminated water.
 99. (canceled) 